A possible source of spin-polarized electrons_ The inert graphene_Ni(111) system
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第一性原理计算简述第一性原理,英文First Principle,是一个计算物理或计算化学专业名词,广义的第一性原理计算指的是一切基于量子力学原理的计算。
我们知道物质由分子组成,分子由原子组成,原子由原子核和电子组成。
量子力学计算就是根据原子核和电子的相互作用原理去计算分子结构和分子能量(或离子),然后就能计算物质的各种性质。
从头算(ab initio)是狭义的第一性原理计算,它是指不使用经验参数,只用电子质量,光速,质子中子质量等少数实验数据去做量子计算。
但是这个计算很慢,所以就加入一些经验参数,可以大大加快计算速度,当然也会不可避免的牺牲计算结果精度。
那为什么使用“第一性原理”这个字眼呢?据说这是来源于“第一推动力”这个宗教词汇。
第一推动力是牛顿创立的,因为牛顿第一定律说明了物质在不受外力的作用下保持静止或匀速直线运动。
如果宇宙诞生之初万事万物应该是静止的,后来却都在运动,是怎么动起来的呢?牛顿相信这是由于上帝推了一把,并且牛顿晚年致力于神学研究。
现代科学认为宇宙起源于大爆炸,那么大爆炸也是有原因的吧。
所有这些说不清的东西,都归结为宇宙“第一推动力”问题。
科学不相信上帝,我们不清楚“第一推动力”问题只是因为我们科学知识不完善。
第一推动一定由某种原理决定。
这个可以成为“第一原理”。
爱因斯坦晚年致力与“大统一场理论”研究,也是希望找到统概一切物理定律的“第一原理”,可惜,这是当时科学水平所不能及的。
现在也远没有答案。
但是为什么称量子力学计算为第一性原理计算?大概是因为这种计算能够从根本上计算出来分子结构和物质的性质,这样的理论很接近于反映宇宙本质的原理,就称为第一原理了。
广义的第一原理包括两大类,以Hartree-Fork自洽场计算为基础的ab initio从头算,和密度泛函理论(DFT)计算。
也有人主张,abinitio专指从头算,而第一性原理和所谓量子化学计算特指密度泛函理论计算。
根据原子核和电子互相作用的原理及其基本运动规律,运用量子力学原理,从具体要求出发,经过一些近似处理后直接求解薛定谔方程的算法,习惯上称为第一原理。
Setting up SCF parametersSCF settings determine the algorithm that CASTEP uses to find the ground state of the electronic subsystem, as well as the accuracy required. Most of these settings do not need to be changed by the user. For example, the SCF tolerance is controlled by the global Quality option on the Setup tab. It can also be modified using the SCF tolerance option on the Electronic tab, however this is not recommended. Similarly, the maximum number of SCF cycles, which can be adjusted using Max. SCF cycles option on the SCF tab on the Electronic Options dialog, need not be changed under normal circumstances. The Max. SCF cycles setting determines how many SCF steps are taken by CASTEP before it moves atoms according to the task being performed (i.e. Geometry Optimization or Dynamics ).Note. The CASTEP server automatically increases the number specified in the interface by a factor of three for metallic systems.Electronic minimization algorithmThe algorithm that is used to solve the DFT equations is specified by the Electronic minimizer option on the SCF tab on the Electronic Options dialog. Density mixing is the recommended choice, in terms of both robustness and efficiency. We found it to be 2-4 times faster for insulators than the conjugate-gradient based All Bands/EDFT scheme. The Density mixing scheme is especially good for metallic systems, where speedups for metal surfaces compared to conjugate gradient schemes are in the region of 10-20. The only case where density mixing may not improve performance is for molecule in a box calculations.The default density mixing settings use Pulay mixing and conjugate-gradient minimization of each electronic state. You should only attempt to change these parameters if SCF is very poor. Sometimes it helps to reduce the length of the DIIS history from the default value of 20 to a smaller value (5-7). It might also be helpful to decrease the mixing amplitude from the default value of 0.5 to 0.1-0.2.Variable electronic states occupanciesBy default CASTEP uses variable electronic occupancies, thus effectively treating all systems as metallic. This is recommended, as it speeds up density mixing optimization, even for systems with large band gaps. The number of empty bands should be sufficiently large to cater for nearly degenerate bands close to the Fermi level. This is relevant for transition or rare earth metal compounds, where narrow d or f bands can be pinned at the Fermi level. If the number of bands used for such a system is insufficient, the SCF will be very slow and probably oscillatory. Occupation numbers of the highest electronic states as reported in the .castep file are likely to be noticeably nonzero for at least some k-points.SCF with the Density mixing minimization scheme can sometimes be poor for metallic systems. If this is the case, the alternative All Bands/EDFT scheme, which is based on the ensemble density-functional theory (Marzari et al., 1997) offers a more robust alternative.Tip. Slow SCF is often indicative of an insufficient number of empty bands, especially in spin-polarized calculations. To check if this is the cause, inspect the occupancies of the highest energy electronic states. They should be very close to zero for all k-points in a calculation which is setup correctly.Further informationSetting up electronic optionsElectronic - CASTEP CalculationSCF - Electronic OptionsDensity Mixing Options - SCF。
版内有这方面的内容顺磁,意味进行non-spin polarized的计算,也就是ISPIN=1。
铁磁,意味进行spin-polarized的计算,ISPIN=2,而且每个磁性原子的初始磁矩设置为一样的值,也就是磁性原子的MAGMOM设置为一样的值。
对非磁性原子也可以设置成一样的非零值(与磁性原子的一样)或零,最后收敛的结果,非磁性原子的local磁矩很小,快接近0,很小的情况,很可能意味着真的是非磁性原子也会被极化而出现很小的local磁矩。
反铁磁,也意味着要进行spin-polarized的计算,ISPIN=2,这是需采用反铁磁的磁胞来进行计算,意味着此时计算所采用的晶胞不再是铁磁计算时的最小原胞。
比如对铁晶体的铁磁状态,你可以采用bcc的原胞来计算,但是在进行反铁磁的Fe计算,这是你需要采用sc的结构来计算,计算的晶胞中包括两个原子,你要设置一个原子的MAGMOM为正的,另一个原子的MAGMOM设置为负,但是它们的绝对值一样。
因此在进行反铁磁的计算时,应该确定好反铁磁的磁胞,以及磁序,要判断哪种磁序和磁胞是最可能的反铁磁状态,那只能是先做好各种可能的排列组合,然后分别计算这些可能组合的情况,最后比较它们的总能,总能最低的就是可能的磁序。
同样也可以与它们同铁磁或顺磁的进行比较。
了解到该材料究竟是铁磁的、还是顺磁或反铁磁的。
亚铁磁,也意味要进行spin-polarized的计算,ISPIN=2,与反铁磁的计算类似,不同的是原子正负磁矩的绝对值不是样大。
非共线的磁性,那需采用专门的non-collinear的来进行计算,除了要设置ISPIN,MAGMOM的设置还需要指定每个原子在x,y,z方向上的大小。
这种情况会复杂一些。
举个例子来说,对于Mn-Cu(001)c(2x2)这种体系,原胞里面有2个Mn原子,那么你直接让两个Mn原子的MAGMOM的绝对值一样,符号相反就可以了,再加上ISPIN=2。
关于计算参数设置主要有几个参数需要注意1 对于Electronic 页面,需要注意的是Core treatment,对于过渡金属原子通常需要考虑相对论效应,因此一般不使用All Electron 方法。
其他几种方法任选。
Basis set 应为DNP,Setup 下的Quality 一般选fine。
为了提高计算速度,一个较好的办法是先用粗糙的Basis set 和Quality 进行优化,然后再提高精度。
2 还有一个非常重要的选项是Electronic>More>SCF 里的Use smearing。
这个关键字有助于加快收敛,但是设的多大往往会产生错误的结果,它也相当于允许的误差范围。
具体设置办法可参考help。
其他的关键字可酌情设置。
Dmol3DMol3允许您使用密度泛函理论(DFT)建模分子、固体和表面的电子结构和能量学。
这将产生非常精确的结果,同时使从头计算方法的计算成本相当低。
您可以使用DMol3研究广泛的系统,包括有机和无机分子、分子晶体、共价固体、金属固体和材料的表面。
使用DMol3,您可以预测结构、反应能量、反应势垒、热力学性质、光学和振动光谱。
DMol3使用DFT产生非常精确的结果,同时对于从头开始的方法保持相当低的计算成本。
您可以在DMol3的理论部分了解更多关于DMol3如何工作的信息。
DMol3适用于分子和三维周期固体,但不适用于一维或二维周期结构。
要为这样的系统建模,您必须构建一个周期性副本之间具有真空的3D结构。
SetupDFT-DSpin unrestricted=spin polarized自旋不受限制:当选择时,表示计算将使用不同的轨道进行不同的自旋。
这就是所谓的“自旋不受限制”或“自旋极化”计算。
如果不加检查,计算对和旋转使用相同的轨道。
这就是所谓的“自旋受限”或“非自旋极化”计算。
默认=无节制的。
Use formal spin as initial使用形式自旋作为初始值:当勾选时,表示每个原子的未配对电子数的初始值将取自为每个原子引入的形式自旋。
a r X i v :h e p -p h /9711228v 1 4 N o v 1997hep-ph/9711228October 1997O (α)QED Corrections to Polarized Elastic µe and Deep Inelastic lN ScatteringDima Bardin a,b,c ,Johannes Bl¨u mlein a ,Penka Christova a,d ,and Lida Kalinovskaya a,caDESY–Zeuthen,Platanenallee 6,D–15735Zeuthen,GermanybINFN,Sezione di Torino,Torino,ItalycJINR,ul.Joliot-Curie 6,RU–141980Dubna,RussiadBishop Konstantin Preslavsky University of Shoumen,9700Shoumen,BulgariaAbstractTwo computer codes relevant for the description of deep inelastic scattering offpolarized targets are discussed.The code µe la deals with radiative corrections to elastic µe scattering,one method applied for muon beam polarimetry.The code HECTOR allows to calculate both the radiative corrections for unpolarized and polarized deep inelastic scattering,including higher order QED corrections.1IntroductionThe exact knowledge of QED,QCD,and electroweak (EW)radiative corrections (RC)to the deep inelastic scattering (DIS)processes is necessary for a precise determination of the nucleon structure functions.The present and forthcoming high statistics measurements of polarized structure functions in the SLAC experiments,by HERMES,and later by COMPASS require the knowledge of the RC to the DIS polarized cross-sections at the percent level.Several codes based on different approaches for the calculation of the RC to DIS experiments,mainly for non-polarized DIS,were developped and thoroughly compared in the past,cf.[1].Later on the radiative corrections for a vast amount of experimentally relevant sets of kinematic variables were calculated [2],including also semi-inclusive situations as the RC’s in the case of tagged photons [3].Furthermore the radiative corrections to elastic µ-e scattering,a process to monitor (polarized)muon beams,were calculated [4].The corresponding codes are :•HECTOR 1.00,(1994-1995)[5],by the Dubna-Zeuthen Group.It calculates QED,QCD and EW corrections for variety of measuremets for unpolarized DIS.•µe la 1.00,(March 1996)[4],calculates O (α)QED correction for polarized µe elastic scattering.•HECTOR1.11,(1996)extends HECTOR1.00including the radiative corrections for polarized DIS[6],and for DIS with tagged photons[3].The beta-version of the code is available from http://www.ifh.de/.2The Programµe laMuon beams may be monitored using the processes ofµdecay andµe scattering in case of atomic targets.Both processes were used by the SMC experiment.Similar techniques will be used by the COMPASS experiment.For the cross section measurement the radiative corrections to these processes have to be known at high precision.For this purpose a renewed calculation of the radiative corrections toσ(µe→µe)was performed[4].The differential cross-section of polarized elasticµe scattering in the Born approximation reads,cf.[7],dσBORNm e Eµ (Y−y)2(1−P e Pµ) ,(1)where y=yµ=1−E′µ/Eµ=E′e/Eµ=y e,Y=(1+mµ/2/Eµ)−1=y max,mµ,m e–muon and electron masses,Eµ,E′µ,E′e the energies of the incoming and outgoing muon,and outgoing electron respectively,in the laboratory frame.Pµand P e denote the longitudinal polarizations of muon beam and electron target.At Born level yµand y e agree.However,both quantities are different under inclusion of radiative corrections due to bremsstrahlung.The correction factors may be rather different depending on which variables(yµor y e)are used.In the SMC analysis the yµ-distribution was used to measure the electron spin-flip asymmetry A expµe.Since previous calculations,[8,9],referred to y e,and only ref.[9]took polarizations into account,a new calculation was performed,including the complete O(α)QED correction for the yµ-distribution,longitudinal polarizations for both leptons,theµ-mass effects,and neglecting m e wherever possible.Furthermore the present calculation allows for cuts on the electron re-coil energy(35GeV),the energy balance(40GeV),and angular cuts for both outgoing leptons (1mrad).The default values are given in parentheses.Up to order O(α3),14Feynman graphs contribute to the cross-section forµ-e scattering, which may be subdivided into12=2×6pieces,which are separately gauge invariantdσQEDdyµ.(2) One may express(2)also asdσQEDdyµ+P e Pµdσpol kk=1−Born cross-section,k=b;2−RC for the muonic current:vertex+bremsstrahlung,k=µµ;3−amm contribution from muonic current,k=amm;4−RC for the electronic current:vertex+bremsstrahlung,k=ee;5−µe interference:two-photon exchange+muon-electron bremsstrahlung interference,k=µe;6−vacuum polarization correction,runningα,k=vp.The FORTRAN code for the scattering cross section(2)µe la was used in a recent analysis of the SMC collaboration.The RC,δA yµ,to the asymmetry A QEDµeshown infigures1and2is defined asδA yµ=A QEDµedσunpol.(4)The results may be summarized as follows.The O(α)QED RC to polarized elasticµe scattering were calculated for thefirst time using the variable yµ.A rather general FORTRAN codeµe la for this process was created allowing for the inclusion of kinematic cuts.Since under the conditions of the SMC experiment the corrections turn out to be small our calculation justifies their neglection. 3Program HECTOR3.1Different approaches to RC for DISThe radiative corrections to deep inelastic scattering are treated using two basic approaches. One possibility consists in generating events on the basis of matrix elements including the RC’s. This approach is suited for detector simulations,but requests a very hughe number of events to obtain the corrections at a high precision.Alternatively,semi-analytic codes allow a fast and very precise evaluation,even including a series of basic cuts andflexible adjustment to specific phase space requirements,which may be caused by the way kinematic variables are experimentally measured,cf.[2,5].Recently,a third approach,the so-called deterministic approach,was followed,cf.[10].It treats the RC’s completely exclusively combining features of fast computing with the possibility to apply any cuts.Some elements of this approach were used inµe la and in the branch of HECTOR1.11,in which DIS with tagged photons is calculated.Concerning the theoretical treatment three approaches are in use to calculate the radiative corrections:1)the model-independent approach(MI);2)the leading-log approximation(LLA); and3)an approach based on the quark-parton model(QPM)in evaluating the radiative correc-tions to the scattering cross-section.In the model-independent approach the QED corrections are only evaluated for the leptonic tensor.Strictly it applies only for neutral current processes.The hadronic tensor can be dealt with in its most general form on the Lorentz-level.Both lepton-hadron corrections as well as pure hadronic corrections are neglected.This is justified in a series of cases in which these corrections turn out to be very small.The leading logarithmic approximation is one of the semi-analytic treatments in which the different collinear singularities of O((αln(Q2/m2l))n)are evaluated and other corrections are neglected.The QPM-approach deals with the full set of diagrams on the quark level.Within this method,any corrections(lepton-hadron interference, EW)can be included.However,it has limited precision too,now due to use of QPM-model itself. Details on the realization of these approaches within the code HECTOR are given in ref.[5,11].3.2O (α)QED Corrections for Polarized Deep Inelastic ScatteringTo introduce basic notation,we show the Born diagramr rr r j r r r r l ∓( k 1,m )l ∓( k 2,m )X ( p ′,M h )p ( p ,M )γ,Z ¨¨¨¨B ¨¨¨¨£¢ ¡£¢ ¡£¢ ¡£¢ ¡£¢ ¡£¢ ¡£¢ ¡£¢ ¡£¢ ¡£¢ ¡z r r r r r r r r r r r r r rr ¨¨¨¨B ¨¨¨¨r r r r j r r r r and the Born cross-section,which is presented as the product of the leptonic and hadronic tensordσBorn =2πα2p.k 1,x =Q 2q 2F 1(x,Q 2)+p µ p ν2p.qF 3(x,Q 2)+ie µνλσq λs σ(p.q )2G 2(x,Q 2)+p µ s ν+ s µ p νp.q1(p.q )2G 4(x,Q 2)+−g µν+q µq νp.qG 5(x,Q 2),(8)wherep µ=p µ−p.qq 2q µ,and s is the four vector of nucleon polarization,which is given by s =λp M (0, n )in the nucleonrest frame.The combined structure functions in eq.(8)F1,2(x,Q2)=Q2e Fγγ1,2(x,Q2)+2|Q e|(v l−p eλl a l)χ(Q2)FγZ1,2(x,Q2)+ v2l+a2l−2p eλl v l a l χ2(Q2)F ZZ1,2(x,Q2),F3(x,Q2)=2|Q e|(p e a l−λl v l)χ(Q2)FγZ3(x,Q2),+ 2p e v l a l−λl v2l+a2l χ2(Q2)F ZZ3(x,Q2),G1,2(x,Q2)=−Q2eλl gγγ1,2(x,Q2)+2|Q e|(p e a l−λl v l)χ(Q2)gγZ1,2(x,Q2),+ 2p e v l a l−λl v2l+a2l χ2(Q2)g ZZ1,2(x,Q2),G3,4,5(x,Q2)=2|Q e|(v l−p eλl a l)χ(Q2)gγZ3,4,5(x,Q2),+ v2l+a2l−2p eλl v l a l χ2(Q2)g ZZ3,4,5(x,Q2),(9) are expressed via the hadronic structure functions,the Z-boson-lepton couplings v l,a l,and the ratio of the propagators for the photon and Z-bosonχ(Q2)=Gµ2M2ZQ2+M2Z.(10)Furthermore we use the parameter p e for which p e=1for a scattered lepton and p e=−1for a scattered antilepton.The hadronic structure functions can be expressed in terms of parton densities accounting for the twist-2contributions only,see[12].Here,a series of relations between the different structure functions are used in leading order QCD.The DIS cross-section on the Born-leveld2σBorndxdy +d2σpol Borndxdy =2πα2S ,S U3(y,Q2)=x 1−(1−y)2 ,(13) and the polarized partdσpol BornQ4λp N f p S5i=1S p gi(x,y)G i(x,Q2).(14)Here,S p gi(x,y)are functions,similar to(13),and may be found in[6].Furthermore we used the abbrevationsf L=1, n L=λp N k 12πSy 1−y−M2xy2π1−yThe O(α)DIS cross-section readsd2σQED,1πδVRd2σBorndx l dy l=d2σunpolQED,1dx l dy l.(16)All partial cross-sections have a form similar to the Born cross-section and are expressed in terms of kinematic functions and combinations of structure functions.In the O(α)approximation the measured cross-section,σrad,is define asd2σraddx l dy l +d2σQED,1dx l dy l+d2σpol radd2σBorn−1.(18)The radiative corrections calculated for leptonic variables grow towards high y and smaller values of x.Thefigures compare the results obtained in LLA,accounting for initial(i)andfinal state (f)radiation,as well as the Compton contribution(c2)with the result of the complete calculation of the leptonic corrections.In most of the phase space the LLA correction provides an excellent description,except of extreme kinematic ranges.A comparison of the radiative corrections for polarized deep inelastic scattering between the codes HECTOR and POLRAD[17]was carried out.It had to be performed under simplified conditions due to the restrictions of POLRAD.Corresponding results may be found in[11,13,14].3.3ConclusionsFor the evaluation of the QED radiative corrections to deep inelastic scattering of polarized targets two codes HECTOR and POLRAD exist.The code HECTOR allows a completely general study of the radiative corrections in the model independent approach in O(α)for neutral current reac-tions including Z-boson exchange.Furthermore,the LLA corrections are available in1st and2nd order,including soft-photon resummation and for charged current reactions.POLRAD contains a branch which may be used for some semi-inclusive DIS processes.The initial state radia-tive corrections(to2nd order in LLA+soft photon exponentiation)to these(and many more processes)can be calculated in detail with the code HECTOR,if the corresponding user-supplied routine USRBRN is used together with this package.This applies both for neutral and charged current processes as well as a large variety of different measurements of kinematic variables. Aside the leptonic corrections,which were studied in detail already,further investigations may concern QED corrections to the hadronic tensor as well as the interference terms. References[1]Proceedings of the Workshop on Physics at HERA,1991Hamburg(DESY,Hamburg,1992),W.Buchm¨u ller and G.Ingelman(eds.).[2]J.Bl¨u mlein,Z.Phys.C65(1995)293.[3]D.Bardin,L.Kalinovskaya and T.Riemann,DESY96–213,Z.Phys.C in print.[4]D.Bardin and L.Kalinovskaya,µe la,version1.00,March1996.The source code is availablefrom http://www.ifh.de/~bardin.[5]A.Arbuzov,D.Bardin,J.Bl¨u mlein,L.Kalinovskaya and T.Riemann,Comput.Phys.Commun.94(1996)128,hep-ph/9510410[6]D.Bardin,J.Bl¨u mlein,P.Christova and L.Kalinovskaya,DESY96–189,hep-ph/9612435,Nucl.Phys.B in print.[7]SMC collaboration,D.Adams et al.,Phys.Lett.B396(1997)338;Phys.Rev.D56(1997)5330,and references therein.[8]A.I.Nikischov,Sov.J.Exp.Theor.Phys.Lett.9(1960)757;P.van Nieuwenhuizen,Nucl.Phys.B28(1971)429;D.Bardin and N.Shumeiko,Nucl.Phys.B127(1977)242.[9]T.V.Kukhto,N.M.Shumeiko and S.I.Timoshin,J.Phys.G13(1987)725.[10]G.Passarino,mun.97(1996)261.[11]D.Bardin,J.Bl¨u mlein,P.Christova,L.Kalinovskaya,and T.Riemann,Acta Phys.PolonicaB28(1997)511.[12]J.Bl¨u mlein and N.Kochelev,Phys.Lett.B381(1996)296;Nucl.Phys.B498(1997)285.[13]D.Bardin,J.Bl¨u mlein,P.Christova and L.Kalinovskaya,Preprint DESY96–198,hep-ph/9609399,in:Proceedings of the Workshop‘Future Physics at HERA’,G.Ingelman,A.De Roeck,R.Klanner(eds.),Vol.1,p.13;hep-ph/9609399.[14]D.Bardin,Contribution to the Proceedings of the International Conference on High EnergyPhysics,Warsaw,August1996.[15]M.Gl¨u ck,E.Reya,M.Stratmann and W.Vogelsang,Phys.Rev.D53(1996)4775.[16]S.Wandzura and F.Wilczek,Phys.Lett.B72(1977)195.[17]I.Akushevich,A.Il’ichev,N.Shumeiko,A.Soroko and A.Tolkachev,hep-ph/9706516.-20-18-16-14-12-10-8-6-4-200.10.20.30.40.50.60.70.80.91elaFigure 1:The QED radiative corrections to asymmetry without experimental cuts.-1-0.8-0.6-0.4-0.200.20.40.60.810.10.20.30.40.50.60.70.80.91elaFigure 2:The QED radiative corrections to asymmetry with experimental cuts.-50-40-30-20-100102030405000.10.20.30.40.50.60.70.80.91HectorFigure 3:A comparison of complete and LLA RC’s in the kinematic regime of HERMES for neutral current longitudinally polarized DIS in leptonic variables.The polarized parton densities [15]are used.The structure function g 2is calculated using the Wandzura–Wilczek relation.c 2stands for the Compton contribution,see [6]for details.-20-100102030405000.10.20.30.40.50.60.70.80.91HectorFigure 4:The same as in fig.3,but for energies in the range of the SMC-experiment.-20-10010203040500.10.20.30.40.50.60.70.80.91HectorFigure 5:The same as in fig.4for x =10−3.-200-150-100-5005010015020000.10.20.30.40.50.60.70.80.91HectorFigure 6:A comparison of complete and LLA RC’s at HERA collider kinematic regime for neutral current deep inelastic scattering offa longitudinally polarized target measuring the kinematic variables at the leptonic vertex.。
U s e r’s G u i d eS I E S T A 2.0.2December12,2008Emilio Artacho University of CambridgeJulian D.Gale Curtin University of Technology,PerthAlberto Garc´ıa Institut de Ci`e ncia de Materials,CSIC,Barcelona Javier Junquera Universidad de Cantabria,SantanderRichard M.Martin University of Illinois at Urbana-ChampaignPablo Ordej´o n Centre de Investigaci´o en Nanoci`e nciai Nanotecnologia,(CSIC-ICN),BarcelonaDaniel S´a nchez-Portal Unidad de F´ısica de Materiales,Centro Mixto CSIC-UPV/EHU,San Sebasti´a n Jos´e M.Soler Universidad Aut´o noma de Madridhttp://www.uam.es/siestasiesta@uam.esCopyright c Fundaci´o n General Universidad Aut´o noma de Madrid:E.Artacho,J.D.Gale,A.Garc´ıa,J.Junquera,P.Ordej´o n,D.S´a nchez-Portal and J.M.Soler,1996-2008Contents1INTRODUCTION4 2VERSION UPDATE63QUICK START63.1Compilation (6)3.2Running the program (6)4PSEUDOPOTENTIAL HANDLING85ATOMIC-ORBITAL BASES IMPLEMENTED IN SIESTA95.1Size:number of orbitals per atom (10)5.2Range:cutoffradii of orbitals (11)5.3Shape (11)6COMPILING THE PROGRAM127INPUT DATA FILE127.1The Flexible Data Format(FDF) (12)7.2General system descriptors (14)7.3Basis definition (16)7.4Lattice,coordinates,k-sampling (21)7.5DFT,Grid,SCF (34)7.6Eigenvalue problem:order-N or diagonalization (46)7.7Molecular dynamics and relaxations (50)7.8Parallel options (56)7.9Efficiency options (57)7.10Output options (57)7.11Options for saving/reading information (61)7.12User-provided basis orbitals (65)7.13Pseudopotentials (65)8OUTPUT FILES658.1Standard output (65)8.2Used parameters (66)18.3Array sizes (66)8.4Basis (66)8.5Pseudopotentials (67)8.6Hamiltonian and overlap matrices (67)8.7Forces on the atoms (67)8.8Sampling k points (67)8.9Charge densities and potentials (67)8.10Energy bands (67)8.11Wavefunction coefficients (68)8.12Eigenvalues (68)8.13Coordinates in specific formats (68)8.14Dynamics historyfiles (68)8.15Force Constant Matrixfile (69)8.16PHONON forcesfile (69)8.17Intermediate and restartfiles (69)9SPECIALIZED OPTIONS7010PROBLEM HANDLING7010.1Error and warning messages (70)10.2Known but unsolved problems and bugs (71)11PROJECTED CHANGES AND ADDITIONS71 12REPORTING BUGS72 13ACKNOWLEDGMENTS72 14APPENDIX:Physical unit names recognized by FDF74 15APPENDIX:NetCDF76 16APPENDIX:Parallel Siesta78 17APPENDIX:XML Output81 18APPENDIX:Selection of precision for storage832Index8331INTRODUCTIONSiesta(Spanish Initiative for Electronic Simulations with Thousands of Atoms)is both a method and its computer program implementation,to perform electronic structure calculations and ab initio molecular dynamics simulations of molecules and solids.Its main characteristics are:•It uses the standard Kohn-Sham selfconsistent density functional method in the local density(LDA-LSD)or generalized gradient(GGA)approximations.•It uses norm-conserving pseudopotentials in its fully nonlocal(Kleinman-Bylander)form.•It uses atomic orbitals as basis set,allowing unlimited multiple-zeta and angular momenta, polarization and off-site orbitals.The radial shape of every orbital is numerical and any shape can be used and provided by the user,with the only condition that it has to be of finite support,i.e.,it has to be strictly zero beyond a user-provided distance from the cor-responding nucleus.Finite-support basis sets are the key for calculating the Hamiltonian and overlap matrices in O(N)operations.•Projects the electron wavefunctions and density onto a real-space grid in order to calculate the Hartree and exchange-correlation potentials and their matrix elements.•Besides the standard Rayleigh-Ritz eigenstate method,it allows the use of localized linear combinations of the occupied orbitals(valence-bond or Wannier-like functions),making the computer time and memory scale linearly with the number of atoms.Simulations with several hundred atoms are feasible with modest workstations.•It is written in Fortran90and memory is allocated dynamically.•It may be compiled for serial or parallel execution(under MPI).(Note:This feature might not be available in all distributions.)It routinely provides:•Total and partial energies.•Atomic forces.•Stress tensor.•Electric dipole moment.•Atomic,orbital and bond populations(Mulliken).•Electron density.And also(though not all options are compatible):•Geometry relaxation,fixed or variable cell.4•Constant-temperature molecular dynamics(Nose thermostat).•Variable cell dynamics(Parrinello-Rahman).•Spin polarized calculations(collinear or not).•k-sampling of the Brillouin zone.•Local and orbital-projected density of states.•Band structure.References:•“Unconstrained minimization approach for electronic computations that scales linearly with system size”P.Ordej´o n,D.A.Drabold,M.P.Grumbach and R.M.Martin,Phys.Rev.B48,14646(1993);“Linear system-size methods for electronic-structure calcula-tions”Phys.Rev.B511456(1995),and references therein.Description of the order-N eigensolvers implemented in this code.•“Self-consistent order-N density-functional calculations for very large systems”P.Ordej´o n,E.Artacho and J.M.Soler,Phys.Rev.B53,10441,(1996).Description of a previous version of this methodology.•“Density functional method for very large systems with LCAO basis sets”D.S´a nchez-Portal,P.Ordej´o n,E.Artacho and J.M.Soler,Int.J.Quantum Chem.,65,453(1997).Description of the present method and code.•“Linear-scaling ab-initio calculations for large and complex systems” E.Artacho, D.S´a nchez-Portal,P.Ordej´o n,A.Garc´ıa and J.M.Soler,Phys.Stat.Sol.(b)215,809 (1999).Description of the numerical atomic orbitals(NAOs)most commonly used in the code, and brief review of applications as of March1999.•“Numerical atomic orbitals for linear-scaling calculations”J.Junquera,O.Paz, D.S´a nchez-Portal,and E.Artacho,Phys.Rev.B64,235111,(2001).Improved,soft-confined NAOs.•“The Siesta method for ab initio order-N materials simulation”J.M.Soler,E.Artacho, J.D.Gale,A.Garc´ıa,J.Junquera,P.Ordej´o n,and D.S´a nchez-Portal,J.Phys.:Condens.Matter14,2745-2779(2002)Extensive description of the Siesta method.•“Computing the properties of materials fromfirst principles with Siesta”,D.S´a nchez-Portal,P.Ordej´o n,and E.Canadell,Structure and Bonding113,103-170(2004).Extensive review of applications as of summer2003.For more information you can visit the web page http://www.uam.es/siesta.The following is a short description of the compilation procedures and of the datafile format for the Siesta code.52VERSION UPDATEIf you have a previous version of Siesta,the update is simply replacing the old siesta directory tree with the new one,saving the arch.makefile that you built to compile Siesta for your architecture(the format of thisfile has changed slightly,but you should be able to translate the immportanfields,such as library locations and compiler switches,to the new version). You also have the option of using the new configure script(see below)to see whether the automatically generated arch.makefile provides anything new or interesting for your setup.If you have workingfiles within the old Siesta tree,including pseudopotential etc.,you will have tofish them out.That is why we recommend working directories outside the package.3QUICK START3.1CompilationUnpack the Siesta distribution.Go to the Src directory,where the source code resides together with the Makefile.You will need afile called arch.make to suit your particular computer setup. The command./configure will start an automatic scan of your system and try to build an arch.make for you.Please note that the configure script might need some help in order tofind your Fortran compiler,and that the created arch.make may not be optimal,mostly in regard to compiler switches,but the process should provide a reasonable workingfile.Type./configure --help to see theflags understood by the script,and take a look at the Src/Confs subdirectory for some examples of their explicit use.You can also create your own arch.make by looking at the examples in the Src/Sys subdirectory.If you intend to create a parallel version of Siesta, make sure you have all the extra support libraries(MPI,scalapack,blacs...).Type make. The executable should work for any job(This is not exactly true,since some of the parameters in the atomic routines are still hardwired(see Src/atmparams.f),but those would seldom need to be changed.)3.2Running the programA fast way to test your installation of Siesta and get a feeling for the workings of the program is implemented in directory Tests.In it you canfind several subdirectories with pre-packaged FDFfiles and pseudopotential references.Everything is automated:after compiling Siesta you can just go into any subdirectory and type make.The program does its work in subdirectory work,and there you canfind all the resultingfiles.For convenience,the outputfile is copied to the parent directory.A collection of reference outputfiles can be found in Tests/Reference. Please note that small numerical and formatting differences are to be expected,depending on the compiler.Other examples are provided in the Examples directory.This directory contains basically the .fdffiles and the pseudopotential generation inputfiles.Since at some point you will have to generate your own pseudopotentials and run your own jobs,we describe here the whole process by means of the simple example of the water-molecule.It is advisable to create independent directories for each job,so that everything is clean and neat,and out of the siesta directory,6so that one can easily update version by replacing the whole siesta tree.Go to your favorite working directory and:$mkdir h2o$cd h2o$cp∼/siesta/Examples/H20/h2o.fdf.We need to generate the required pseudopotentials(We are going to streamline this process for this time,but you must realize that this is a tricky business that you must master before using Siesta responsibly.Every pseudopotential must be thoroughly checked before use.Please refer to the ATOM program manual in∼/siesta/Pseudo/atom/Docs for details regarding what follows.)$cd∼/siesta/Pseudo/atom$makeNow the pseudopotential-generation program,called atm,should be compiled(you might want to change the definition of the compiler in the makefile).$cd Tutorial/O$cat O.tm2.inpThis is the inputfile,for the oxygen pseudopotential,that we have prepared for you.It is in a standard(but obscure)format that you will need to understand in the future:------------------------------------------------------------pg Oxygentm2 2.0n=O c=ca0.00.00.00.00.00.01420 2.000.0021 4.000.00320.000.00430.000.001.15 1.15 1.15 1.15------------------------------------------------------------To generate the pseudopotential do the following;$sh../pg.sh O.tm2.inpNow there should be a new subdirectory called O.tm2(O for oxygen)and O.tm2.vps(unfor-matted)and O.tm2.psf(ASCII)files.$cp O.tm2.psf∼/whateveryourworkingdir/h2o/O.psfcopies the generated pseudopotentialfile to your working directory.(The unformatted and ASCIIfiles are functionally equivalent,but the latter is more transportable and easier to look at,if you so desire.)The same could be repeated for the pseudopotential for H,but you may as well copy H.psf from siesta/Examples/Vps/to your h2o working directory.7Now you are ready to run the program:siesta<h2o.fdf|tee h2o.out(If you are running the parallel version you should use some other invocation,such as mpirun -np2siesta...,but we cannot go into that here.)After a successful run of the program,you should have manyfiles in your directory including the following:•out.fdf(contains all the data used,explicit or default-ed)•O.ion and H.ion(complete information about the basis and KB projectors)•h2o.XV(contains thefinal positions and velocities)•h2o.STRUCT OUT(contains thefinal cell vectors and positions in“crystallographic”format)•h2o.DM(contains the density matrix to allow a restart)•h2o.ANI(contains the coordinates of every MD step,in this case only one)•h2o.FA(contains the forces on the atoms)•h2o.EIG(contains the eigenvalues of the Kohn-Sham Hamiltonian)•h2o.out(standard output)•h2o.xml(XML marked-up output)The Systemlabel.out is the standard output of the program,that you have already seen passing on the screen.Have a look at it and refer to the output-explanation section if necessary.You may also want to look at the out.fdffile to see all the default values that siesta has chosen for you,before studying the input-explanation section and start changing them.Now look at the other datafiles in Examples(all with an.fdf suffix)choose one and repeat the process for it.4PSEUDOPOTENTIAL HANDLINGThe atomic pseudopotentials are stored either in binaryfiles(with extension.vps)or in ASCII files(with extension.psf),and are read at the beginning of the execution,for each species defined in the inputfile.The datafiles must be named*.vps(or*.psf),where*is the label of the chemical species(see the ChemicalSpeciesLabel descriptor below).Thesefiles are generated by the ATOM program(read siesta/Pseudo/atom/README for more complete authorship and copyright acknowledgements).It is included(with permission)in siesta/Pseudo/atom.Remember that all pseudopotentials should be thoroughly tested before using them.We refer you to the standard literature on pseudopotentials and to the ATOM manual siesta/Pseudo/atom/atom.tex.85ATOMIC-ORBITAL BASES IMPLEMENTED IN SIESTA The main advantage of atomic orbitals is their efficiency(fewer orbitals needed per electron for similar precision)and their main disadvantage is the lack of systematics for optimal convergence, an issue that quantum chemists have been working on for many years.They have also clearly shown that there is no limitation on precision intrinsic to LCAO.This section provides some information about how basis sets can be generated for Siesta.It is important to stress at this point that neither the Siesta method nor the program are bound to the use of any particular kind of atomic orbitals.The user can feed into Siesta the atomic basis set he/she choses by means of radial tables(see User.Basis below),the only limitations being:(i)the functions have to be atomic-like(radial functions mutiplied by spherical harmonics),and(ii)they have to be offinite support,i.e.,each orbital becomes strictly zero beyond some cutoffradius chosen by the user.Most users,however,do not have their own basis sets.For these users we have devised some schemes to generate reasonable basis sets within the program.These bases depend on several parameters per atomic species that are for the user to choose,and can be important for both quality and efficiency.A description of these bases and some performance tests can be found in“Numerical atomic orbitals for linear-scaling calculations”J.Junquera,O.Paz,D.S´a nchez-Portal,and E.Artacho,Phys.Rev.B64235111,(2001)An important point here is that the basis set selection is a variational problem and,therefore, minimizing the energy with respect to any parameters defining the basis is an“ab initio”way to define them.We have also devised a quite simple and systematic way of generating basis sets based on specifying only one main parameter(the energy shift)besides the basis size.It does not offer the best NAO results one can get for a given basis size but it has the important advantages mentioned above.More about it in:“Linear-scaling ab-initio calculations for large and complex systems”E.Artacho,D.S´a nchez-Portal,P.Ordej´o n,A.Garc´ıa and J.M.Soler,Phys.Stat.Sol.(b)215,809(1999).In addition to Siesta we provide the program Gen-basis,which reads Siesta’s input and generates basisfiles for later use.Gen-basis is compiled automatically at the same time as Siesta.It should be run from the Tutorials/Bases directory,using the gen-basis.sh script. It is limited to a single species.In the following we give some clues on the basics of the basis sets that Siesta generates.The starting point is always the solution of Kohn-Sham’s Hamiltonian for the isolated pseudo-atoms, solved in a radial grid,with the same approximations as for the solid or molecule(the same exchange-correlation functional and pseudopotential),plus some way of confinement(see below). We describe in the following three main features of a basis set of atomic orbitals:size,range, and radial shape.95.1Size:number of orbitals per atomFollowing the nomenclature of Quantum Chemistry,we establish a hierarchy of basis sets,from single-ζto multiple-ζwith polarization and diffuse orbitals,covering from quick calculations of low quality to high precision,as high as thefinest obtained in Quantum Chemistry.A single-ζ(also called minimal)basis set(SZ in the following)has one single radial function per angular momentum channel,and only for those angular momenta with substantial electronic population in the valence of the free atom.It offers quick calculations and some insight on qualitative trends in the chemical bonding and other properties.It remains too rigid,however,for more quantitative calculations requiring both radial and angularflexibilization.Starting by the radialflexibilization of SZ,a better basis is obtained by adding a second function per channel:double-ζ(DZ).In Quantum Chemistry,the split valence scheme is widely used: starting from the expansion in Gaussians of one atomic orbital,the most contracted gaussians are used to define thefirst orbital of the double-ζand the most extended ones for the second.For strictly localized functions there was afirst proposal of using the excited states of the confined atoms,but it would work only for tight confinement(see PAO.BasisType nodes below).This construction was proposed and tested in D.S´a nchez-Portal et al.,J.Phys.:Condens.Matter8, 3859-3880(1996).We found that the basis set convergence is slow,requiring high levels of multiple-ζto achieve what other schemes do at the double-ζlevel.This scheme is related with the basis sets used in the OpenMX project[see T.Ozaki,Phys.Rev.B67,155108(2003);T.Ozaki and H.Kino, Phys.Rev.B69,195113(2004)].We then proposed an extension of the split valence idea of Quantum Chemistry to strictly localized NAO which has become the standard and has been used quite succesfully in many systems(see PAO.BasisType split below).It is based on the idea of suplementing thefirst ζwith,instead of a gaussian,a numerical orbital that reproduces the tail of the original PAO outside a matching radius r m,and continues smoothly towards the origin as r l(a−br2),with a and b ensuring continuity and differenciability at r m.Within exactly the same Hilbert space, the second orbital can be chosen to be the difference between the smooth one and the original PAO,which gives a basis orbital strictly confined within the matching radius r m(smaller than the original PAO!)continuously differenciable throughout.Extra parameters have thus appeared:one r m per orbital to be doubled.The user can again introduce them by hand(see PAO.Basis below).Alternatively,all the r m’s can be defined at once by specifying the value of the tail of the original PAO beyond r m,the so-called split norm.Variational optimization of this split norm performed on different systems shows a very general and stable performance for values around15%(except for the∼50%for hydrogen).It generalizes to multiple-ζtrivially by adding an additional matching radius per new zeta. Angularflexibility is obtained by adding shells of higher angular momentum.Ways to generate these so-called polarization orbitals have been described in the literature for Gaussians.For NAOs there are two ways for Siesta and Genbasis to generate them:(i)Use atomic PAO’s of higher angular momentum with suitable confinement,and(ii)solve the pseudoatom in the presence of an electricfield and obtain the l+1orbitals from the perturbation of the l orbitals by thefield.Finally,the method allows the inclusion of offsite orbitals(not centered around any specific10atom).The orbitals again can be of any shape,including atomic orbitals as if an atom would be there(useful for calculating the counterpoise correction for basis-set superposition errors). Bessel functions for any radius and any excitation level can also be added anywhere to the basis set.5.2Range:cutoffradii of orbitalsStrictly localized orbitals(zero beyond a cutoffradius)are used in order to obtain sparse Hamil-tonian and overlap matrices for linear scaling.One cutoffradius per angular momentum channel has to be given for each species.A balanced and systematic starting point for defining all the different radii is achieved by giving one single parameter,the energy shift,i.e.,the energy raise suffered by the orbital when confined.Allowing for system and physical-quantity variablity,as a rule of thumb∆E PAO≈100meV gives typical precisions within the accuracy of current GGA functionals.The user can,nevertheless,change the cutoffradii at will.5.3ShapeWithin the pseudopotential framework it is important to keep the consistency between the pseudopotential and the form of the pseudoatomic orbitals in the core region.The shape of the orbitals at larger radii depends on the cutoffradius(see above)and on the way the localization is enforced.Thefirst proposal(and quite a standard among Siesta users)uses an infinite square-well poten-tial.It was oroginally proposed and has been widely and succesfully used by Otto Sankey and collaborators,for minimal bases within the ab initio tight-binding scheme,using the Fireball program,but also for moreflexible bases using the methodology of Siesta.This scheme has the disadavantage,however,of generating orbitals with a discontinuous derivative at r c.This discontinuity is more pronounced for smaller r c’s and tends to disappear for long enough values of this cutoff.It does remain,however,appreciable for sensible values of r c for those orbitals that would be very wide in the free atom.It is surprising how small an effect such kink produces in the total energy of condensed systems.It is,on the other hand,a problem for forces and stresses,especially if they are calculated using a(coarse)finite three-dimensional grid. Another problem of this scheme is related to its defining the basis considering the free atoms. Free atoms can present extremely extended orbitals,their extension being,besides problematic, of no practical use for the calculation in condensed systems:the electrons far away from the atom can be described by the basis functions of other atoms.A traditional scheme to deal with this is the one based on the radial scaling of the orbitals by suitable scale factors.In addition to very basic bonding arguments,it is soundly based on restoring virial’s theorem forfinite bases,in the case of coulombic potentials(all-electron calculations).The use of pseudopotentials limits its applicability,allowing only for extremely small deviations from unity(∼1%)in the scale factors obtained variationally(with the exception of hydrogen that can contract up to25%).This possiblity is available to the user.Another way of dealing with that problem and that of the kink at the same time is adding a soft confinement potential to the atomic Hamiltonian used to generate the basis orbitals: it smoothens the kink and contracts the orbital as suited.Two additional parameters are11introduced for the purpose,which can be defined again variationally.The confining potential is flat(zero)in the core region,starts offat some internal radius r i with all derivatives continuous and diverges at r c ensuring the strict localization there.It isV(r)=V o e−r c−r ir−r ir c−r(1)and both r i and V o can be given to Siesta together with r c in the input(see PAO.Basis below). Finally,the shape of an orbital is also changed by the ionic character of the atom.Orbitals in cations tend to shrink,and they swell in anions.Introducing aδQ in the basis-generating free-atom calculations gives orbitals better adapted to ionic situations in the condensed systems. More information about basis sets can be found in the proposed literature.The directory Tutorials/Bases in the main Siesta distribution contains some tutorial ma-terial for the generation of basis sets and KB projectors.6COMPILING THE PROGRAMThe compilation of the program is done using a Makefile that is provided with the code.This Makefile will generate the executable for any of several architectures,with a minimum of tuning required from the user in a separatefile called arch.make to reside in the Src/directory.The instructions are in directory siesta/Src/Sys,where there are also a number of.makefiles already prepared for several architectures and operating sistems.If none of thesefit your needs, you will have to prepare one on your own.The command$./configurewill start an automatic scan of your system and try to build an arch.make for you.Please note that the configure script might need some help in order tofind your Fortran compiler,and that the created arch.make may not be optimal,mostly in regard to compiler switches,but the process should provide a reasonable workingfile.Type./configure--help to see theflags understood by the script,and take a look at the Src/Confs subdirectory for some examples of their explicit use.You canfine tune arch.make by looking at the examples in the Src/Sys subdirectory.If you intend to create a parallel version of Siesta,make sure you have all the extra support libraries(MPI,scalapack,blacs...).After arch.make is ready,ype make.The executable should work for any job(This is not exactly true,since some of the parameters in the atomic routines are still hardwired(see Src/atmparams.f),but those would seldom need to be changed.)7INPUT DATA FILE7.1The Flexible Data Format(FDF)The main inputfile,which is read as the standard input(unit5),contains all the physical data of the system and the parameters of the simulation to be performed.Thisfile is written in a12special format called FDF,developed by Alberto Garc´ıa and Jos´e M.Soler.This format allows data to be given in any order,or to be omitted in favor of default values.Refer to documentation in∼/siesta/Src/fdf for details.Here we offer a glimpse of it through the following rules:•The FDF syntax is a’data label’followed by its value.Values that are not specified in the datafile are assigned a default value.•FDF labels are case insensitive,and characters-.in a data label are ignored.Thus, LatticeConstant and lattice constant represent the same label.•All text following the#character is taken as comment.•Logical values can be specified as T,true,.true.,yes,F,false,.false.,no.Blank is also equivalent to true.•Character strings should not be in apostrophes.•Real values which represent a physical magnitude must be followed by its units.Look at function fdf convfac infile∼/siesta/Src/fdf/fdf.f for the units that are currently supported.It is important to include a decimal point in a real number to distinguish it from an integer, in order to prevent ambiguities when mixing the types on the same input line.•Complex data structures are called blocks and are placed between‘%block label’and a ‘%endblock label’(without the quotes).•You may‘include’other FDFfiles and redirect the search for a particular data label to anotherfile.If a data label appears more than once,itsfirst appearance is used.These are some examples:SystemName Water molecule#This is a commentSystemLabel h2oSpinPolarized yesSaveRhoNumberOfAtoms64LatticeConstant 5.42Ang%block LatticeVectors1.0000.0000.0000.000 1.0000.0000.0000.000 1.000%endblock LatticeVectorsKgridCutoff<BZ_sampling.fdf#Reading the coordinates from a file%block AtomicCoordinatesAndAtomicSpecies<coordinates.data#Even reading more FDF information from somewhere else%include mydefaults.fdf13。
Centro de Investigaci´o n y de Estudios Avanzados del IPN Departamento de Ingenier´ıa El´e ctrica2nd International Conference on Electrical and Electronics Engineering(ICEEE)XI Conference on Electrical Engineering(CIE2005)Mexico City,MexicoSeptember7-9,2005Final Program&Abstract BookThis book was elaborated using L A T E X2e. CINVESTAV,August2005ContentsMessage from the conference chair4 Message from the Head of the EED5 2nd ICEEE-CIE Organizing Committee7 Topic Chairs8 Reviewers9 Final Program11 Courses19 Round table sessions21 General Information21 Keynote Speakers22 Plenary Conferences Abstracts23 Abstract Book27 Autor Index63Message from the conference chairWe begin our joint Conference,namely ICEEE-CIE2005,with the desire to meet col-leagues and friends from Mexico and abroad.We mean students,professors and pro-fessionals that design,develop and propose technological and engineering solutions for electrical and electronics systems,whether as research work or immediate application. Certainly,this Conference is an opportunity to do so.It is worth pointing out that it is the second time this technical forum is presented as an international event and whose diffusion has been excellent due to the means of the prestigious institution:the Institute of Electrical and Electronics Engineers,IEEE.In this respect,we are also grateful to Cinvestav by its support providing facilities andfinances.Looking at the ICEEE-CIE2005program,we can mention that the technical topics cover a wide spectrum of areas,namely in computer science,bioelectronics,communica-tion systems,solid-state electronics,VLSI design,electronic materials and mechatronics. They reflect modern engineering techniques and methods,which belong to those proposed by experienced experts that work in academia,laboratories and industry,in collaboration with students and specialized technicians.In summary,we are going to witness relevant results that might help ours,fulfilling the early objectives of this Conference.We realize that the quality of the selected papers for oral presentation is high due in part to the participation of foreign reviewers,who kindly accepted the silent task of eval-uating the original manuscripts in collaboration with national ones.We recognize that the participation of keynote speakers is a cornerstone on which this Conference builds its success.In particular,five full professors,each one invited by the Sections of the host Electrical Engineering Department,enhance this issue.Some words for visitors from abroad follow.Mexico is a modern Spanish-speaker coun-try,where the friendship is a distinctive gesture that foreigners always appreciate,there-fore,this event is a vehicle to try.Our city,which is taken into account as the largest in the world,is also warm even though its thoughtful people and Cinvestav is not the exception to the rule.In the context of both the initial preparation and thefinal process of setting details of the Conference,we want to thank to Mrs.Carmen Quintero,Judith Esparza,Anabel D´ıaz,Miguel-Angel Velasco,Emilio Espinosa,Gabriel Vega Mart´ınez and student Victor Ponce for offering their timely and valuable skills.Finally,on behalf of the ICEEE-CIE2005organizing committee I welcome to everyone attending this fruitful three-day academic meeting.Likewise,enjoy your stay in our city! Sincerely,Felipe G´o mez-Casta˜n edaICEEE-CIE2005Conference Chair.Message from the Head of the EEDDear Coleagues:On behalf of the Electrical Engineering Department(EED)at the Center of Research and Advanced Studies(Cinvestav),it is my privilege to welcome you to the Second In-ternational Conference on Electrical and Electronics Engineering(ICEEE)and the XI Conference on Electrical Engineering(CIE).This occasion is quite special since we are celebrating eleven years of the CIE which has been organized as an annual event by the EED.Furthermore,we are initiating today a new adventure:The ICEEE organized for the this time in the EED’s Mexico city main campus.As you know,this time our venue is M´e xico,City where we expect an intensive interaction among scholars and electrical engineering practitioners from all over the world,especially,from the Americas.One of the main objectives of the ICEEE is to provide a forum to spread and promote the disciplines cultivated by the EED,namely:Bioelectronics,Communications,Com-puter Science,Mechatronics and Solid State Electronics.Likewise,this event represents an opportunity to make known scientific and technological contributions achieved by other Mexican institutes.Throughout its forty two years of existence and as its most important reason to be, the EED faculty has strived to promote science and technology in Mexico.Such task has not been only limited to pure academic developments but also has decisively con-tributed to improvements and developments in a variety of national industry products and applications.That is why the ICEEE and CIE-2005conferences have always had the presence of industry representatives whose participation we welcome.In this sense,the ICEEE comes to crown and consecrate the entire academic and research efforts of the EED faculty during all these years.Given the rich diversity of Electrical Engineering disciplines cultivated by the EED,an international and national committee in different specialties was assembled together to perform a rigorous review process of the submitted papers.In this way,we are in the position to guarantee both,the quality of the conference and the benefit that all delegates can obtain from attending our ICEEE/CIEEE-2005conference.Attendees willfind that there is a lot to learn from the scientific and technological exchange to be provided by this forum.Assistance willfind an opportunity to increase their awareness of nowadays most relevant electrical engineering problems.For all the aforementioned,this even constitutes a high priority means to promote the technological advanced of our countries.Another milestone achieved recently by Cinvestav was our graduate student number 5324.Out of this number,the EED alone has contributed with824graduated students,be-ing the highest number ever obtained by any Electrical Engineering post-graduate school in Mexico.Finally,on behalf of all the faculty member of the EED,I would like to thank all those who have worked so hard to make these conferences possible.Particularly,we are grateful to our director,Rosalinda Contreras,to IEEE and to our sponsors for all the support given to us towards the organization of this event.We hope that you will enjoy the Conferences and that you willfind some free time to relax and get to know the Mexico city.Ernesto SuasteHead of the EED2nd ICEEE-CIE Organizing Committee Dr.Felipe G´o mez-Casta˜n eda(Conference Chairman)Dr.Carlos Alvarado-Serrano(Proceedings Editor)Dr.Rafael Castro-Linares(Tutorials)Dr.Luis Gerardo de la Fraga(Technical Program)Dr.Felipe Alejandro Cruz-P´e rez(Advertising)Dr.Ernesto Suaste-G´o mez(Industrial Relations and Exhibit)Dra.Xiaoou Li Zhang(Logistics)Technical SupportJudith Esparza(System and On-Line Submission)Ma.del Carmen Quintero(Administrative Assistant)Ricardo G´o mez(Exhibiting Assistant)Conference Management System CINVESTAV(On-Line Paper Submission and Reviewing System)Topic Chairs Bioengineering and Medical Electronics Electrical PowerElectronic CircuitsCarlos Alvarado SerranoCINVESTAV-IPN. Communication SystemsMauricio Lara-Barr´o nCINVESTAV-IPN.Computer ScienceXiaoou Li ZhangCINVESTAV-IPN.Solid-State Electronics and VLSI Semiconductor MaterialsMar´ıa de la Luz Olvera-AmadorCINVESTAV-IPN.Automatic Control and Mechatronics Rafael Castro-LinaresCINVESTAV-IPN.ReviewersAbraham Claudio S´a nchez.........................................CENIDET,M´e xico Aldo Orozco...............................................CINVESTAV-IPN,M´e xico Alfonso Guti´e rrez Aldana...........................................CIC-IPN,M´e xico Andr´e s Iv´a n Oliva Arias...................................CINVESTAV-IPN,M´e xico Ante Salcedo Gonz´a lez.................................................ITAM,M´e xico Antonio F Mondragon Torres..............................Texas Instruments,U.S.A. Arturo Escobosa...........................................CINVESTAV-IPN,M´e xico Arturo Hern´a ndez Aguirre............................................CIMAT,M´e xico Arturo Morales-Acevedo...................................CINVESTAV-IPN,M´e xico Arturo Veloz Guerrero...................................................Intel,M´e xico Arturo Vera Hern´a ndez....................................CINVESTAV-IPN,M´e xico Carlos A.Coello Coello....................................CINVESTAV-IPN,M´e xico Carlos Alberto Cruz Villar.................................CINVESTAV-IPN,M´e xico Carlos Alvarado Serrano...................................CINVESTAV-IPN,M´e xico Carlos Arist´o teles De La Cruz Blas...........Universidad P´u blica de Navarra,Espa˜n a Christopher Druzgalski...............................................CSULB,U.S.A. Claude Moog........................................................IRCCyN,France David H.Covarrubias Rosales.......................................CICESE,M´e xico Demetrio Villanueva Ayala.................................CINVESTAV-IPN,M´e xico Deni L.Torres Rom´a n.....................................CINVESTAV-IPN,M´e xico Dominique boratoire LSR Logiciels Systemes Resea,France Edgar Ch´a vez.............Universidad Michoacana de San Nicol´a s de Hidalgo,M´e xico Eduardo Moreno.............................................ICIMAF,CITMA,Cuba Ernesto Suaste.............................................CINVESTAV-IPN,M´e xico Felipe Alejandro Cruz P´e rez...............................CINVESTAV-IPN,M´e xico Felipe G´o mez Casta˜n eda...................................CINVESTAV-IPN,M´e xico Fernando Ram´ırez Mireles.............................................ITAM,M´e xico Francisco Javier Garc´ıa Ugalde................Facultad de Ingenier´ıa,UNAM,M´e xico Francisco J.Garc´ıa S´a nchez....................Universidad Sim´o n Bol´ıvar,Venezuela Francisco J.Ruiz-S´a nchez..................................CINVESTAV-IPN,M´e xico Francisco Rodr´ıguez-Henr´ıquez.............................CINVESTAV-IPN,M´e xico Gabriel Romero Paredes Rubio............................CINVESTAV-IPN,M´e xico Giselle M.Galv´a n-Tejada..................................CINVESTAV-IPN,M´e xico Guang-Bin Huang.......................Nanyang Technological University,Singapore Guillermo Morales-Luna...................................CINVESTAV-IPN,M´e xico Henri Huijberts................................University of London,United Kingdom Horacio Soto Ortiz..................................................CICESE,M´e xico Ieroham Baruch...........................................CINVESTAV-IPN,M´e xico Isaac Rudomin.................................................ITESM-CEM,M´e xico Javier E.Gonz´a lez Villarruel.........................................ITESM,M´e xico Jes´u s Carrillo L´o pez...........................................BUAP,Puebla,M´e xico Joaquin Alvarez.....................................................CICESE,M´e xico Jorge Carlos Mex Perera.........................ITESM,Campus Monterrey,M´e xicoJos´e Alfredo´Alvarez-Ch´a vez.............University of Southampton,United Kingdom Jos´e Luis Medina Monroy...........................................CICESE,M´e xico Jos´e Luis Ramos Quirarte........................Universidad de Guadalajara,M´e xico Jos´e Miguel Rocha P...............Freescale Semiconductor,Motorola Puebla,M´e xico Jose Rosario Gallardo Lopez.........................................CICESE,M´e xico Juan Humberto Sossa Azuela.......................................CIC-IPN,M´e xico Juan Manuel Hern´a ndez Cid..........................................ITESO,M´e xico Luis Gerardo de la Fraga...................................CINVESTAV-IPN,M´e xico Manuel Duarte-Mermoud.................................Universidad de Chile,Chile Maria De La Luz Olvera Amador..........................CINVESTAV-IPN,M´e xico Mariano Aceves Mijares......................................INAOE,Puebla,M´e xico Mario Alfredo Reyes Barranca.............................CINVESTAV-IPN,M´e xico Mauricio Lara.............................................CINVESTAV-IPN,M´e xico Mauricio Ortega L´o pez....................................CINVESTAV-IPN,M´e xico M´a ximo L´o pez-L´o pez......................................CINVESTAV-IPN,M´e xico MengChu Zhou...........................................................NJIT,USA Miguel´Angel Le´o n Ch´a vez....................................BUAP,Puebla,M´e xico Miguel Garc´ıa-Rocha......................................CINVESTAV-IPN,M´e xico Mohamed Moustafa Abd-El Aziz Moustafa.......The Cabinet-Information&DecisionSupport.Egypt Oscar Castillo...............................Instituto Tecnol´o gico de Tijuana,M´e xico Oscar D´ıaz...................................University of the Basque Country,Spain Pablo Rogelio Hern´a ndez Rodr´ıguez........................CINVESTAV-IPN,M´e xico Rafael Castro-Linares......................................CINVESTAV-IPN,M´e xico Ram´o n Mart´ın Rodr´ıguez Dagnino...............ITESM,Campus Monterrey,M´e xico Ram´o n Parra Michel............................ITESM Campus Guadalajara,M´e xico Ram´o n Pe˜n a Sierra........................................CINVESTAV-IPN,M´e xico Ricardo G´o mez Villanueva.................................CINVESTAV-IPN,M´e xico Roberto Mu˜n oz Guerrero..................................CINVESTAV-IPN,M´e xico Rodolfo Quintero Romo....................................CINVESTAV-IPN,M´e xico Rogelio Alc´a ntara Silva.......................Facultad de Ingenier´ıa,UNAM,M´e xico Valeri Kontorovich Mazover................................CINVESTAV-IPN,M´e xico Vicente Parra Vega........................................CINVESTAV-IPN,M´e xico Xiaoou Li..................................................CINVESTAV-IPN,M´e xico Yasuhiro Matsumoto.......................................CINVESTAV-IPN,M´e xicoFinal ProgramWednesday7,September2005Auditory Room1Room2 8:309:30Registration9:309:50Opening Ceremony10:0011:00PLE1EP11SSE1111:0011:30Break Break Break11:3012:30CS1EP12SSE1212:3013:30CS1MEC11BIO1113:3015:00Lunch Lunch Lunch15:0016:00CS2MEC12BIO1216:0017:00CS2COM1BIO217:0018:00-COM1BIO218:00-Welcome cocktailThrusday8,September2005Auditory Room1Room2 9:0010:00COM2SSE2BIO3 10:0011:00PLE2SSE2BIO3 11:0011:30Break Break Break 11:3012:30PLE3COM3EP2 12:3013:30Round-T1COM3EP2 13:3015:00Lunch Lunch Lunch 15:0017:00CS31MEC21EP3 17:0017:30Break Break–17:3018:10CS32MEC22–Friday9,September2005Auditory Room1Room2 9:0010:00–EC1SEM1 10:0011:00PLE4EC1SEM1 11:0011:30Break Break Break 11:3012:30PLE5EC2SEM2 12:3014:00Round-T2EC2SEM2 14:00-Closing CeremonySymbol list:PLE PlenaryBIO Bioengineering and Medical ElectronicsCOM Communication SystemsCS Computer ScienceSSE Solid-State Electronics and VLSIMEC Mechatronics and Automatic ControlEC Electronic CircuitsSEM Semiconductor MaterialsEP Electrical PowerRound-T Round Table1CS1Computer ScienceWednesday11:30-13:30AuditoryChair:Dr.Luis Gerardo de la Fraga..................1.111:30-11:50.An Algorithm for Reduct of Boolean Functions Basedon Primes (27)1.211:50-12:10.A Virtual Machine for the Ambient Calculus (27)1.312:10-12:30.Algorithms for Robust Graph Coloring on Paths (27)1.412:30-12:50.Animation of Deformable Objects Built with SimplexMeshes (27)1.512:50-13:10.Mathematical Tools for Speeding Up the Determina-tion of Configurations of the n-Dimensional Orthogonal Pseudo-Polytopes (28)1.613:10-13:30.Non-Linear Filters for colour imaging implemented byDSP (28)2CS2Computer ScienceWednesday15:00-17:00AuditoryChair:Dra.Xiaoou Li...........................2.115:00-15:20.Environmental Sounds Recognition System Using theSpeech Recognition System Techniques (28)2.215:20-15:40.Analysis of Audio Watermarking Schemes (29)2.315:40-16:00.Wavelet Domain Statistical Order Filter using the Tri-State Median Filter Algorithm (29)2.416:00-16:20.Analysis of a DFT-Based Watermarking Algorithm..292.516:20-16:40.Implementation of Artificial Neural Networks for Recog-nition of Target and Clutter Images (30)2.616:40-17:00.SIMD Architecture for Image Segmentation using So-bel Operators Implemented in FPGA Technology (30)3CS31Computer ScienceThursday15:00-17:00AuditoryChair:Dr.Arturo D´ıaz P´e rez.......................3.115:00-15:20.Mobile RFID Reader with Database Wireless Synchro-nization (30)3.215:20-15:40.Experimental Analysis of Wireless Propagation Modelswith Mobile Computing Applications (31)3.315:40-16:00.Performance Analysis of the Confidentiality SecurityService in the IEEE802.11using WEP,AES-CCM,and ECC (31)3.416:00-16:20.A Tool for Analysis of Internet Metrics (31)3.516:20-16:40.A Library Framework for the POSIX Application-Defined Scheduling Proposal (31)3.616:40-17:00.Dynamic invocation of Web services by using aspect-oriented programming (32)4CS32Computer ScienceThursday17:30-18:10AuditoryChair:Dr.Arturo D´ıaz P´e rez.......................4.117:30-17:50.LIDA/REC Visual Language for Databases interfacePostgreSQL (32)4.217:50-18:10.Aspect-Oriented Web Services Orchestration (33)5COM1Communication SystemsWednesday16:00-18:00Room1Chair:Dr.Aldo Gustavo Orozco Lugo.................5.116:00-16:20.Adaptive Echo Canceller Using a Modified LMS Algo-rithm (33)5.216:20-16:40.The Universality of the Prolate Spheroidal Wave Func-tions for Channel Orthogonalization and its Modeling (33)5.316:40-17:00.On the generalized and modified Suzuki model(GMSM):approximations and level crossing statistics (34)5.417:00-17:20.On MIMO Space-Time Coded Systems:Unleashingthe Spatial Domain (34)5.517:20-17:40.On the design of an FPGA-Based OFDM modulatorfor IEEE802.11a (34)5.617:40-18:00.DSP Digital Modulation Software Implementation andRF Impairments Analysis (35)6COM2Communication SystemsThursday9:00-10:00AuditoryChair:Dr.Javier Gonz´a lez........................6.19:00-9:20.State of the Art in Ultra-Wideband Antennas (35)6.29:20-9:40.Design and Simulation of a1to14GHz BroadbandElectromagnetic Compatibility DRGH Antenna (35)6.39:40-10:00.RF System Concepts Applied to Digital Wireless Re-ceivers Design Based on wireless standards (36)7COM3Communication SystemsThursday11:30-13:30Room1Chair:Dra.Giselle Galv´a n Tejada...................7.111:30-11:50.Design of a Backup Wireless Network for the Depart-ment of Electrical Engineering of CINVESTAV-IPN (36)7.211:50-12:10.Cell Planning Based on the WiMax Standard for HomeAccess:A Practical Case (36)7.312:10-12:30.Performance Analysis of an All-Optical WavelengthConverter Using a Semiconductor Optical Amplifier Simulator (37)7.412:30-12:50.Quasi Mobile IP-based Architecture for Seamless In-terworking between WLAN and GPRS Networks (37)7.512:50-13:10.Design and Verification Based on Assertions:SomeStatistics (37)7.613:10-13:30.Traffic Analysis for IP Telephony (38)8BIO11Bioengineering and Medical ElectronicsWednesday12:30-13:30Room2Chair:Dr.Pablo Rogelio Hern´a ndez Rodr´ıguez...........8.112:30-12:50.A Microprocessor-Based System for Pulse-Echo Over-lap Measurement of Ultrasonic Velocity (38)8.212:50-13:10.Rotation Effects of an Axicon Ultrasonic Transducerwhen Measuring a Blood Flow Rate (38)8.313:10-13:30.Experimental Estimation of Acoustic Attenuation andDispersion (38)9BIO12Bioengineering and Medical ElectronicsWednesday15:00-16:00Room2Chair:Dr.Pablo Rogelio Hern´a ndez Rodr´ıguez...........9.115:00-15:20.New X-wave Solutions of Isotropic/Homogenous ScalarWave Equation (39)9.215:20-15:40.Feasibility study of using ultrasonic transducer borderwaves for centering hydrophones in ultrasonicfield characterization399.315:40-16:00.ELF magneticfields generator,variable in intensityand frequency for biological applications (39)10BIO2Bioengineering and Medical ElectronicsWednesday16:00-18:00Room2Chair:Dr.Roberto Mu˜n oz Guerrero..................10.116:00-16:20.Automatic Detection of ECG Ventricular ActivityWaves using Continuous Spline Wavelet Transform (40)10.216:20-16:40.Crayfish Brain States Characterization with WaveletTransform (40)10.316:40-17:00.Measurement of Skin-Electrode Impedance for a12-lead Electrocardiogram (41)10.417:00-17:20.Cancer Model Identification Via Sliding Mode andDifferential Neural Networks (41)10.517:20-17:40.Experimental Seat for the Study of the Effects of Ran-dom Pneumatic Stimulation for the Prevention of Pressure Ulcers.41 11BIO3Bioengineering and Medical ElectronicsThursday9:00-11:00Room2Chair:Dr.Arturo Vera Hern´a ndez...................11.19:00-9:20.Foveal model of artificial retina with phototransistors inDarlington configuration in the high-resolution region (42)11.29:20-9:40.Distributed Retinal Stimulation Model Based on Adap-tive System (42)11.39:40-10:00.Chromatic Pupillary Response in Diabetic Patients (42)11.410:00-10:20.Neuro Tracking Control for Glucose-Insulin InteractionModel (43)11.510:20-10:40.PVDF Strength Sensor for Biomechanical Analysis inMice (43)11.610:40-11:00.Conception and Realization of a3D Dynamic Sensoras a Tool in Human Walking Study (43)12MEC11Mechatronics and Automatic ControlWednesday12:30-13:30Room1Chair:Dr.Gerardo Silva Navarro....................12.112:30-12:50.New Results on the Energy-Based Control of SeriesResonant Inverters (44)12.212:50-13:10.Modeling and Controller Design of a Magnetic Levita-tion System (44)12.313:10-13:30.Global observability and detectability analysis for aclass of nonlinear models of biological processes with bad inputs..44 13MEC12Mechatronics and Automatic ControlWednesday15:00-16:00Room1Chair:Dr.Gerardo Silva Navarro....................13.115:00-15:20.On New Passivity Property:Review and Extension toMechanical Rotational Systems (44)13.215:20-15:40.Fault Detection Using Dynamic Principal ComponentAnalysis by Average Estimation (45)14MEC21Mechatronics and Automatic ControlThursday15:20-17:00Room1Chair:ardo Aranda Bricaire..................14.115:20-15:40.Stability of a diamond-type quasipolynomial family..4514.215:40-16:00.Lyapunov Matrices for Time Delay Systems (45)14.316:00-16:20.Lyapunov Matrices for Neutral Type Time Delay Sys-tems (45)14.416:20-16:40.Solving the Coupled Riccati Equation for the N-PlayersLQ Differential Game (46)14.516:40-17:00.Improving Stability and Performance in a GeneralizedMinimum Variance Controller using Dynamic Pole Assignment (46)15MEC22Mechatronics and Automatic ControlThursday17:30-18:50Room1Chair:Dr.Vicente Parra Vega......................15.117:30-17:50.Stable Task Space Neurocontroller for Robot Manipu-lators without Jacobian Matrix (46)15.217:50-18:10.New Position Controllers for Robot Manipulators (46)15.318:10-18:30.A design strategy of discrete event controllers for au-tomated manufacturing systems (47)15.418:30-18:plexity and Path Planning for a car-like robot..47 16SSE11Solid-State Electronics and VLSIWednesday10:00-11:00Room2Chair:Dr.Alfredo Reyes Barranca...................16.110:00-10:20.Morphological effects and their relation with the elec-trical resistivity measured during the initial stages of growth ofAu/glas (47)16.210:20-10:40.Charging/discharging effects in nc-Si/SiO2superlat-tice prepared by LPCVD (48)16.310:40-11:00.Effect of Nitrogen in the Photoluminescence of SiliconRich Oxidefilms prepared by LPCVD (48)17SSE12Solid-State Electronics and VLSIWednesday11:30-12:30Room2Chair:Dr.Alfredo Reyes Barranca...................17.111:30-11:50.SnO2,SnO2/Ag and Ag/SnO2Thin Films used asPropane Sensors (48)17.211:50-12:10.Two-Dimensional Nonlinear Spin-Dipole Waves in theMillimeter Wave Range (48)18SSE2Solid-State Electronics and VLSIThursday9:00-11:00Room1Chair:Dr.Jos´e A.Moreno Cadenas..................18.19:00-9:20.Polyimide Passivation Approaches on Double-Mesa Thyris-tors (49)18.29:20-9:40.A Low-Power Bootstrapped CMOS Full Adder (49)18.39:40-10:00.An Improved EKV Model for Partially Depleted SOIDevices (49)18.410:00-10:20.Macromodel for CMOS Photogate-Type Active PixelSensors (50)18.510:20-10:40.Linear theory of the thermoelectric cooling based onthe Peltier effect (50)18.610:40-11:00.Fuzzy Equalizer in VLSI (50)18.711:00-11:20.1-D BJT Parameter Extraction for Cuasi-3D Simula-tion of Four-Layer Devices (50)19EP11Electrical PowerWednesday10:00-11:00Room1Chair:Ing.Jos´e A.Urbano Castel´a n..................19.110:00-10:20.Modeling of the Circuit Parameters of an Induction De-vice for Heating of a Non-Magnetic Conducting Cylinder by Meansof a Travel (51)19.210:20-10:ing Edsa on Radial Primary Feeder Capacitor Sizeand Location Simulation (51)19.310:40-11:00.A Complex Fault-Tolerant Power System Simulation.51 20EP12Electrical PowerWednesday11:30-12:30Room1Chair:Ing.Jos´e A.Urbano Castel´a n..................20.111:30-11:50.Internal Winding Faults in Three-Phase Five-LimbTransformer (52)20.211:50-12:10.Analysis of the generator-transformer interaction inthe abc reference (52)21EP2Electrical PowerThursday11:30-13:30Room2Chair:Dr.Francisco Ru´ız S´a nchez...................21.111:30-11:50.Dinamics of Solar-Powerwd Fractional Horse PowerMotor (52)21.211:50-12:10.Sliding Mode Observer-Based Control for a Series Ac-tive Filter (53)21.312:10-12:30.Fuzzy Logic Enhanced Speed Control System of a VSI-Fed Three Phase Induction motor (53)21.412:30-12:50.Intelligent Control of the Regenerative Braking in anInduction Motor Drive (53)21.512:50-13:10.Analysis of Propulsion Systems in Electric Vehicles..54 22EP3Electrical PowerThursday15:20-17:00Room2Chair:To be defined............................22.115:20-15:40.Electrical Network Simulation for Increasing Quality.5422.215:40-16:00.A trust-region algorithm based on global SQP for re-active power optimization (54)22.316:00-16:20.Stability Analysis of Power Market with Bounded Ra-tionality Cournot Game (54)22.416:20-16:40.A RBFN Hierarchical Clustering Based Network Parti-tioning Method for Zonal Pricing (55)23EC1Electronic CircuitsFriday9:40-11:00Room1Chair:Dr.Hildeberto Jard´o n Aguilar.................23.19:40-10:00.MMIC Differential Amplifier Implementation Based onRF&MW Analytical Tools (55)23.210:00-10:20.900MHz band class E PA using high voltage n-channeltransistors in standard CMOS technology (56)23.310:20-10:40.Efficient Design Approach for a SiGe HBT OscillatorIncorporating Reflection Sapphire Loaded Cavity Resonator (56)。
(2)研究分子基功能材料的设计、合成和组装方法,发展稀土功能分子的组装、复合和原理器件制备技术,研究分子基功能体系的结构与其磁性、发光、光/电、磁/电、电/光转换和耦合性质的关系规律和理论机制,为开发新型分子基功能材料和原理器件提供依据;设计、合成具有高效活化小分子(H2O, H2, O2, CH4, CH3OH,CO, CH2=CH2)功能的稀土/过渡金属分子基体系,研究其催化反应及机理;7)发展复杂大体系的密度泛函计算方法,研究相对论效应对含重元素体系性质的影响,探寻含重元素(特别是稀土元素)功能材料的性能与其电子结构间的关系规律,发展镧系理论,为稀土功能体系的设计提供依据。
并行计算机群和多台SGI O2工作站等。
spintronics自旋电子学自旋电子学是利用载流子(电子与电子空穴)自旋传导的电子学,英文Spintronics是利用spin transport electronics的字首及字尾组合而成。
当初系美国国防部高级研究计划局(Defense Advanced Research Project Agency)(DARPA)于1994年开始支持发展的项目。
其目的系创造新一代的电子元件,它除了利用载流子的电学特性,还要利用到载流子的自旋特性。
由于自旋有两个状态(Spin up and Spin down),这在磁盘信息存储中常被用来代表二进制的两个基础代码"0"和"1"。
因此,与传统只利用电荷载流特性的器件相比,利用到自旋的电子元件将同时拥有信息存储的功能。
目前已发展出的元件是利用与自旋有关的穿隧效应以及巨大磁阻(GMR:Giant Magnetoresistance)效应来作磁场侦测器,以及磁随机存取记忆体(MRAM:magnetic random access memory)。
另外正在发展的元件有自旋开关,调变器电晶体及一些传统无法做到的新型元件。
MS软件常见问题及解决办法1、问:用MS构造晶体时要先确立空间群,可是那些空间群的代码是啥意思啊,看不懂,我想做的是聚乙烯醇的晶体,嘿嘿,也不知道去哪可以查到它的空间群答:A、要做晶体,首先要查询晶体数据,然后利用晶体数据再建立模型。
晶体数据来源主要是文献,或者一些数据库,比如CCDC。
你都不知道这个晶体是怎么样的,怎么指定空间群呢?要反过来做事情哦:)B、我不知道你指示的代码是数字代码还是字母代码,数字代码它对应了字母的代码,而字母的代码它含盖了一些群论的知识(晶系,对称操作等),如果要具体了解你的物质或者材料属于那一个群,你可以查阅一下相关的手册,当然你要了解一些基本的群论知识.MS自带了一些材料的晶体结构,你可以查询一下.2、问:各位高手,我用ms中的castep进行运算。
无论cpu是几个核心,它只有一个核心在工作。
这个怎么解决呢?答:请先确认以下几个问题:1,在什么系统下装,是否装了并行版本。
2,计算时设置参数的地方是否选择了并行。
3,程序运算时,并不是时时刻刻都要用到多个CPU3、问:我已经成功地安装了MS3.1的Linux版本,串行的DMol3可以成功运行。
但是运行并行的时候出错。
机器是双Xeon5320(四核)服务器,rsh和rlogin均开启,RHEL4.6系统。
其中hosts.equiv的内容如下:localhostibm-consolemachines.LINUX的内容如下:localhost:8现在运行RunDMol3.sh时,脚本停在$MS_INSTALL_ROOT/MPICH/bin/mpirun $nolocal -np $nproc $MS_INSTALL_ROOT/DMol3/bin/dmol3_mpi.exe $rootname$DMOL3_DATA这一处,没法执行这一命令并行运算时,出现以下PIxxxx(x为数字)输出ibm-console 0 /home/www/MSI/MS3.1/DMol3/bin/dmol3_mpi.exelocalhost 3 /home/www/MSI/MS3.1/DMol3/bin/dmol3_mpi.exe请问这是什么原因?谢谢!答:主要是rsh中到ibm-console的没有设置把/etc/hosts改为127.0.0.1 localhost.localdomain localhost ibm-console在后面加个ibm-console也希望对大家有帮助!4、问:在最后结果的dos图中,会显示不同电子spd的贡献,我想问的是,假设MS考虑的原子Mg的电子组态为2p6 3s2,那么最后的dos结果中的s,p是不是就是2p,跟3s的贡献.比如更高能量的3p是否可能出现在dos中?如果可能的话,在这种情况下,如何区分2p和3p的贡献,谢谢.答:A、取决于你的餍势势里面没有3p电子,DOS怎么会有呢?自然,你的1p1s也不会出现在你的DOS中。
A possible source of spin-polarized electrons: The inert graphene/Ni(111) systemYu. S. Dedkov, M. Fonin, and C. LaubschatCitation: Appl. Phys. Lett. 92, 052506 (2008); doi: 10.1063/1.2841809View online: /10.1063/1.2841809View Table of Contents: /resource/1/APPLAB/v92/i5Published by the American Institute of Physics.Related ArticlesA graphene solution to conductivity mismatch: Spin injection from ferromagnetic metal/graphene tunnel contacts into siliconJ. Appl. Phys. 113, 17C502 (2013)A simple formulation for magnetoresistance in metal-insulator granular films with increased currentJ. Appl. Phys. 113, 073911 (2013)Enhanced inverse spin-Hall effect in ultrathin ferromagnetic/normal metal bilayersAppl. Phys. Lett. 102, 072401 (2013)Devices with electrically tunable topological insulating phasesAppl. Phys. Lett. 102, 063503 (2013)Very large magnetoresistance and spin state transition in Ba-doped cobaltitesJ. Appl. Phys. 113, 053909 (2013)Additional information on Appl. Phys. Lett.Journal Homepage: /Journal Information: /about/about_the_journalTop downloads: /features/most_downloadedInformation for Authors: /authorsA possible source of spin-polarized electrons:The inert graphene/Ni…111…systemYu.S.Dedkov,1,a͒M.Fonin,2and ubschat11Institut für Festkörperphysik,Technische Universität Dresden,01062Dresden,Germany2Fachbereich Physik,Universität Konstanz,78457Konstanz,Germany͑Received2October2007;accepted1January2008;published online6February2008͒We report on an investigation of spin-polarized secondary electron emission from the chemicallyinert system:graphene/Ni͑111͒.An ordered passivation graphene layer͑monolayer of graphite͒wasformed on Ni͑111͒surface via cracking of propylene gas.The spin polarization of secondaryelectrons obtained from this system upon photoemission is only slightly lower than the one from theclean Ni surface but does not change upon large oxygen exposure.These results suggest to use suchpassivated Ni͑111͒surface as a source of spin-polarized electrons stable against adsorption ofreactive gases.©2008American Institute of Physics.͓DOI:10.1063/1.2841809͔Recently,graphene͑monolayer of graphite͒has attracted renewed interest due to the possible application of this ma-terial in carbon-based nanoelectronics.It was shown theoretically1as well as experimentally2,3that electrons move through graphene sheets as if they have no rest masses. In the same experimental work,an unusual form of the quan-tum Hall effect was also observed.The peculiar band struc-ture of graphene,a single sp2bonded carbon layer,possesses conical electron and hole pockets which meet only at the K points of the Brillouin zone in momentum space.2,4Due to the linear dependence of energy on momentum,the carriers behave as effectively massless,relativistic Dirac fermions with an effective speed of light of c eff=106m/s,as described by Dirac’s equation.From a technological point of few the observation of large carrier mobilities of up to 60000cm2V−1s−1at4K and15000cm2V−1s−1at300K together with a bipolarfield effect5is most intriguing.For semiconductor-electronic applications,graphite layers can be grown on SiC͑0001͒surfaces in high structural quality.In recent work,similar intriguing properties in ultrathin graph-ite layers grown on SiC were found and it was suggested that this may open a route toward graphene-based electronics.6 Weakly bonded with substrate graphene layers can also be prepared on top of a Ni͑111͒substrate followed by interca-lation of thin layers of noble metals͑Cu,Ag,and Au͒under-neath graphene layer.7–9On the other hand,stable nonreactive graphene layers on top of ferromagnetic materials͑Ni͒͑Refs.7–9͒may be used as sources of spin-polarized electrons.Electron sources are used in all domains ranging from technical devices of daily life such as cathode-ray tubes to large-scale scientific experi-ments such as electron accelerators.While the energy distri-bution and the average kinetic energy of the electrons can easily be controlled byfine tuning of the electron emission parameters͑such as bias potential and temperature of the source͒,the control over the spin polarization of the electron beam is difficult.The latter is of great interest for particle physics experiments and for studies of magnetic systems in condensed matter physics,including the burgeoningfield of spintronics.In the present work,we report on spin-polarized electron emission from the graphene/Ni͑111͒system before and after exposure to oxygen.It is shown that the spin polarization of secondary electrons at zero kinetic energy from graphene/ Ni͑111͒system is reduced by about1/3with respect to onefrom the clean Ni͑111͒surface but contrasting to the latter,itremains practically unaffected upon oxygen exposure.Theseexperimental observations open technical perspectives forapplication of graphite layers in spintronic devices.Investigations of the graphene/Ni͑111͒system were per-formed in the experimental setup for spin-resolved electronspectroscopy consisting of two chambers:preparation andanalysis.As a substrate,the W͑110͒single crystal was used.Prior to preparation of the studied system,the well estab-lished cleaning procedure of the W substrate was applied:several cycles of oxygen treatment with subsequentflashes at2300°C.A well ordered Ni͑111͒surface was prepared bythermal deposition of Nifilms with a thickness of about100Åonto a clean W͑110͒substrate and subsequent anneal-ing at300°C.The corresponding low-energy electron dif-fraction͑LEED͒pattern is shown in the upper left corner ofFig.1.An ordered graphene overlayer was prepared viacracking of propylene gas͑C3H6͒according to the recipe described in Ref.7.The LEED spots of the graphene/Ni͑111͒system reveal a well-ordered p͑1ϫ1͒overstructure as ex-pected from the small lattice mismatch of only1.3%͑Fig.1,upper panel,center͒.After the cracking procedure,theNi͑111͒surface is completely covered by graphenefilm asdemonstrated by scanning tunneling microscopy͑STM͒.STM images of the graphitized Ni͑111͒surface,acquired atroom temperature and at+0.05V͑left͒and−0.04V͑right͒sample bias voltages,respectively,are shown in Fig.1͑middle panel͒.All investigated terraces display the same atomic structure showing three different levels of apparent heights͑Fig.1,right-hand image in the middle panel͒.The distance between the two atoms within A or B graphene sub-lattices͑bright maxima or dark minima͒was measured to be 2.4Ϯ0.1Åbeing in good agreement with the expected in-teratomic spacings of2.46Åin graphene.Spin-and angle-resolved photoemission spectra were re-corded at1486.6eV͓Al K␣,x-ray photoemission spectros-copy͑XPS͔͒and40.8eV͓He II␣ultraviolet photoemission spectroscopy͑UPS͔͒photon energies,respectively,using aa͒Author to whom correspondence should be addressed.Electronic mail:dedkov@physik.phy.tu-dresden.de.APPLIED PHYSICS LETTERS92,052506͑2008͒0003-6951/2008/92͑5͒/052506/3/$23.00©2008American Institute of Physics92,052506-1hemispherical energy analyzer SPECS PHOIBOS 150com-bined with a 25kV mini-Mott detector for spin analysis.10The energy resolution of the analyzer was set to 100and 500meV for UPS and XPS,respectively.The spin polariza-tion of secondary electrons in XPS spectra was analyzed with an energy resolution of 200meV.Spin-resolved mea-surements were performed in magnetic remanence after hav-ing applied a magnetic field pulse of about 1kOe along thein-plane ͗11¯0͘easy axis of the Ni ͑111͒film.The experimen-tal setup asymmetry was accounted for in the standard way by measuring spin-resolved spectra for two opposite direc-tions of applied magnetic field.11,12The electronic structure of the graphene/Ni ͑111͒system was studied in detail by means of angle-resolved photoemis-sion in earlier work.7,13Here,we show only a few angle-resolved valence-band photoemission spectra of the system under study ͑Fig.1,lower panel ͒.The spectra were takenwith He II ␣radiation along the ⌫¯-M¯direction of the surface Brillouin zone ͑Fig.1,upper right corner ͒and are in good agreement with previous data.7,13In the same figure,the pho-toemission spectrum of a pure graphite single crystal mea-sured in normal emission geometry is shown by a shaded area.From a comparison of the photoemission spectra of graphene/Ni ͑111͒and pure graphite,one may conclude that the difference in binding energy of the states amounts to about 2.3eV,which is close to the value observed earlier 7,13and in good agreement with the theoretical prediction of2.35eV.14This shift reflects the effect of hybridization of the graphene bands with the Ni 3d bands and,secondary,with the Ni 4s and 4p states.These results indicate high quality graphene monolayer on top of the Ni ͑111͒surface.The inert properties of the graphene/Ni ͑111͒system were tested by exposure to oxygen for 30min at a partial O 2pressure of 5ϫ10−6mbar and room temperature.The results are compiled in Fig.2where a series of Ni 2p XPS spectra are shown,taken from the pure Ni ͑111͒surface ͑spectrum 1͒,from freshly prepared graphene/Ni ͑111͒͑spectrum 2͒,and after exposure of graphene/Ni ͑111͒and Ni ͑111͒to oxygen ͑spectra 3and 4,respectively ͒.The inset of Fig.2shows O 1s XPS spectra obtained from the last two systems.In all spectra,the Ni 2p emission consists of a spin-orbit doublet ͑2p 3/2,1/2͒and a well-known satellite structure.The main line is ascribed to a completely screened final state ͑c −13d 104s 1͒and the satellite to a two-hole bound state ͑c −13d 94s 2͒,where c −1stands for the ͑Ar ͒core with a 2p hole.For the pure Ni ͑111͒film,the satellite appears with respect to the main lines at 6eV higher binding energy,whereas this shift is increased approximately by 0.9eV for the graphene/Ni ͑111͒system.This effect reflects the altered chemical environment at the interface and is not the subject of the present discus-sion.From the comparison of spectra 2and 3,it becomes clear that the exposure to oxygen does not affect the spectral shape of the graphene/Ni ͑111͒system.It shows that the graphene overlayer prevents obviously the interaction of oxygen with the underlying Ni substrate which would be reflected by strong modifications of satellite structure of the Ni 2p spectra ͑compare spectrum 4͒.The intensity of the O 1s photoemission signal of the graphene/Ni ͑111͒system after oxygen exposure is very weak as compared to the one of the pure Ni surface upon the same treatment ͑compare inset of Fig.2͒.From this observation,one may conclude that the sticking coefficient of oxygen on the graphene overlayer is extremely low and the overlayer is almost free of defects that may allow oxygen atoms to access the Ni substrate.From these facts,one may suggest that a Ni ͑111͒passivatedbyFIG.1.͑Color online ͒Upper panel,from left to right:LEED patterns from pure Ni ͑111͒and graphene/Ni ͑111͒surfaces and corresponding surface Bril-louin zone of the system with main symmetric points.Middle panel:con-stant current STM images of the high quality graphene/Ni ͑111͒surface ob-tained at +0.05V ͑left ͒and −0.04V ͑right ͒bias voltages,respectively.Lower panel:photoelectron spectra of the graphene/Ni ͑111͒system takenwith h =40.8eV photon energy along ⌫¯-M ¯direction of the surface Bril-louin zone are presented for several emission angles ͑marked on the left-hand side of each spectra ͒;for comparison,a spectrum of pure graphite taken in normal emission geometry is shown by the shadedarea.FIG. 2.͑Color online ͒Ni 2p core-level spectra of Ni ͑111͒,graphene/Ni ͑111͒,and systems obtained after exposure of the respective surfaces to oxygen.The inset shows O 1s XPS spectra obtained after exposure of Ni ͑111͒and graphene/Ni ͑111͒surfaces to large amounts of oxygen,respectively.graphene may serve as an extremely inert source of spin-polarized electrons.This idea was tested experimentally by measuring the spin polarization P of the secondary electrons of the systems under study.Here,P is defined as normalized difference of the numbers of the emitted spin-up and spin-down electrons.The spin polarization of the low kinetic energy tail of the photoelectron spectrum of the ferromagnetic Ni ͑111͒film ͑see Fig.3,open circles ͒is in good agreement with previ-ously published results.15–18The spin polarization of second-ary electrons at kinetic energies of about 10eV is equal to the one of the valence band electrons.A strong enhancement of the spin polarization appears at kinetic energies below Ϸ3eV.This enhancement was interpreted as due to ex-change scattering between the hot electrons and the 3d va-lence electrons,19,20the leading term being the “spin-flip”processes of the Stoner excitations.Monte-Carlo simulations 19showed that the strongly enhanced polarization near zero kinetic energy still scales with magnetization of the sample M .The situation is very favorable for applications as surface magnetometer or source of spin-polarized electrons:the maximum of polarization coincides with the maximum of the intensity I and the intensity of true secondary electrons is generally very large,orders of magnitude larger than the in-tensities of elastically scattered electrons or photoelectrons.Figure 3shows the spin polarization of the secondary electrons as measured for the pure Ni ͑111͒surface ͑open circles ͒,graphene/Ni ͑111͒͑filled circles ͒,O 2+graphene /Ni ͑111͒͑half-filled squares ͒,and O 2+Ni ͑111͒͑open triangles ͒.As compared to the clean Ni ͑111͒surface,the spin polarization of secondary electrons emitted from the graphene/Ni ͑111͒system is reduced from Ϸ17%to Ϸ12%.The reduction of P due to the graphene overlayer can be explained by the strong hybridization between Ni 3d and graphene states that is supported by theory 14,21and previ-ous angle-resolved photoemission experiments.7,13Since the spin polarization of secondary electrons is roughly propor-tional to the magnetic moment at the surface of a ferromag-netic material,15–18one can estimate that in the graphene/Ni ͑111͒system,the magnetic moment of Ni atoms at the interface amounts to about 0.52B as compared to 0.72Bfor the pure Ni ͑111͒surface.14This reduction is consistent with the values obtained in a recent theoretical work.14Ad-ditional reduction of the magnetic moment can be explained by spin-flip scattering of electrons in the polarized graphene layer or/and scattering by structural defects.22The interesting observation is that exposure to oxygen at high partial pressure does not affect the shape of the spin-polarization curve.Particularly,the spin polarization of elec-trons at the vacuum level ͑zero kinetic energy ͒remains al-most the same ͑the slight reduction by 2%is within error bar ͒.This is in strong contrast to the behavior of the clean Ni ͑111͒surface where exposure to oxygen leads to a com-plete quenching of the spin polarization ͑compare Fig.3͒.In conclusion,we studied emission of spin-polarized secondary electrons from the graphene/Ni ͑111͒system and found that exposure to large amounts of oxygen does not affect the magnitude of spin polarization.The phenomenon is explained by a passivation of the Ni surface by a closed graphene overlayer that inhibits oxygen adsorption and direct contact of Ni atoms with the reactive gas.We suggest that such an inert system may be used as chemically inert source of spin-polarized electrons.This work was funded by the Deutsche Forschungsge-meinschaft ͑SFB 463TP B4͒.1I.A.Luk’yanchuk 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