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Questions about the magnetic moment in NEGF calculations Date: 2019/07/17 21:46 Name: H Y ZHOU Dear all, I'm trying to calculate TMR of the Fe/MgO/Fe system. However, the magnetic moments of Fe atoms always seem strange. The magnetic moments of interfacial Fe atoms, which are about 1.29μB, are much lower than usual ones. However, I don't know why this phenomenon occurs and if I should change some parameters, such as NEGF.Num.Poles, scf.ElectronicTemperature or scf.energycutoff. Looking forward to your reply. Thank you very much in advance. Best, H Y Following is part of the .md file which is the NEGF calculation result. time= 0.000 (fs) Energy= -1387.17333 (Hartree) Cell_Vectors= 27.70100 0.00000 0.00000 0.00000 2.83000 0.00000 0.00000 0.00000 2.83000 atom x y z magnetic moment Fe 0.00000 1.41500 1.41500 2.22110 Fe 1.41600 0.00000 0.00000 2.22688 Fe 2.83200 1.41500 1.41500 2.12162 Fe 4.24800 0.00000 0.00000 1.29266 O 6.48100 0.00000 0.00000 0.00698 O 8.70150 1.41500 1.41500 0.00018 O 10.92200 0.00000 0.00000 -0.00004 O 13.14250 1.41500 1.41500 -0.00000 O 15.36300 0.00000 0.00000 -0.00004 O 17.58350 1.41500 1.41500 0.00018 O 19.80400 0.00000 0.00000 0.00699 Mg 6.48100 1.41500 1.41500 -0.04765 Mg 8.70150 0.00000 0.00000 0.00224 Mg 10.92200 1.41500 1.41500 0.00005 Mg 13.14250 0.00000 0.00000 0.00002 Mg 15.36300 1.41500 1.41500 0.00005 Mg 17.58350 0.00000 0.00000 0.00224 Mg 19.80400 1.41500 1.41500 -0.04765 Fe 22.03700 0.00000 0.00000 1.29263 Fe 23.45300 1.41500 1.41500 2.12160 Fe 24.86900 0.00000 0.00000 2.22688 Fe 26.28500 1.41500 1.41500 2.22110 Here is my input file. NEGF.Num.Poles 200 # default=150 NEGF.scf.Kgrid 7 7 # default=1 1 NEGF.scf.Iter.Band 10 # defalut=6 No idea about what's this NEGF.Output.for.TranMain off # on NEGF.bias.voltage 0.0 # default=0.0 (eV) NEGF.bias.neq.im.energy 0.01 # default=0.01 (eV) NEGF.bias.neq.energy.step 0.02 # default=0.02 (eV) NEGF.tran.CurrentDensity off NEGF.tran.Channel off NEGF.tran.energydiv 201 # default=200 NEGF.tran.energyrange -5 5 1e-3 # default=-10.0 10.0 1.0e-3 (eV) NEGF.tran.Kgrid 120 120 # default= 1 1 Dos.fileout off # on|off, default=off NEGF.Dos.energyrange -15.0 25.0 5.0e-3 #default=-10.0 10.0 5.0e-3 (eV) NEGF.Dos.energy.div 200 # default=200 NEGF.Dos.Kgrid 7 7 # default=1 1 # # Definition of Atomic Species # Species.Number 3 <Definition.of.Atomic.Species Fe Fe5.0H-s2p2d1 Fe_PBE13H Mg Mg7.0-s2p2 Mg_PBE13 O O5.0-s2p2d1 O_PBE13 Definition.of.Atomic.Species> # # Atoms # Atoms.SpeciesAndCoordinates.Unit Ang # Ang|AU Atoms.Number 14 <Atoms.SpeciesAndCoordinates 1 O 6.481 0.000 0.000 3.0 3.0 2 O 8.7015 1.415 1.415 3.0 3.0 3 O 10.9220 0.000 0.000 3.0 3.0 4 O 13.1425 1.415 1.415 3.0 3.0 5 O 15.3630 0.000 0.000 3.0 3.0 6 O 17.5835 1.415 1.415 3.0 3.0 7 O 19.8040 0.000 0.000 3.0 3.0 8 Mg 6.481 1.415 1.415 4.0 4.0 9 Mg 8.7015 0.000 0.000 4.0 4.0 10 Mg 10.9220 1.415 1.415 4.0 4.0 11 Mg 13.1425 0.000 0.000 4.0 4.0 12 Mg 15.3630 1.415 1.415 4.0 4.0 13 Mg 17.5835 0.000 0.000 4.0 4.0 14 Mg 19.8040 1.415 1.415 4.0 4.0 Atoms.SpeciesAndCoordinates> # # Lead-Left # LeftLeadAtoms.Number 4 <LeftLeadAtoms.SpeciesAndCoordinates # Unit=Ang. 1 Fe 0.000 1.415 1.415 9.0 7.0 2 Fe 1.416 0.000 0.000 9.0 7.0 3 Fe 2.832 1.415 1.415 9.0 7.0 4 Fe 4.248 0.000 0.000 9.0 7.0 LeftLeadAtoms.SpeciesAndCoordinates> # # Lead-Right # RightLeadAtoms.Number 4 <RightLeadAtoms.SpeciesAndCoordinates # Unit=Ang. 1 Fe 22.0370 0.000 0.000 9.0 7.0 2 Fe 23.4530 1.415 1.415 9.0 7.0 3 Fe 24.8690 0.000 0.000 9.0 7.0 4 Fe 26.2850 1.415 1.415 9.0 7.0 RightLeadAtoms.SpeciesAndCoordinates> # # SCF or Electronic System # scf.XcType GGA-PBE # LDA|LSDA-CA|LSDA-PW|GGA-PBE scf.SpinPolarization On # On|Off|NC scf.SpinOrbit.Coupling Off # On|Off, default=off scf.ElectronicTemperature 300.0 # default=300 (K) scf.energycutoff 220.0 # default=150 (Ry) scf.maxIter 5000 # default=40 scf.EigenvalueSolver NEGF # DC|GDC|Cluster|Band #scf.lapack.dste dstevx # dstegr|dstedc|dstevx, default=dstegr scf.Kgrid 1 7 7 # means n1 x n2 x n3 scf.Mixing.Type rmm-diisk # Simple|Rmm-Diis|Gr-Pulay|Kerker|Rmm-Diisk scf.Kerker.factor 20.0 # default=1 scf.Init.Mixing.Weight 0.01 # default=0.30 scf.Min.Mixing.Weight 0.001 # default=0.001 scf.Max.Mixing.Weight 0.01 # default=0.40 scf.Mixing.History 20 # default=5 scf.Mixing.StartPulay 20 # default=6 scf.Mixing.EveryPulay 1 # default=6 scf.criterion 1.0e-6 # default=1.0e-6 (Hartree)

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