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Transport direction in 2D slab NEGF calculation Date: 2018/09/28 15:58 Name: ZHOU Jiaqi   <jiaqi.zhou@buaa.edu.cn> Dear all, I have a problem on the transport direction in 2D slab NEGF calculation. In my lead input file I set a square unit cell to make the transport along a axis, as the following: Atoms.UnitVectors.Unit Ang <Atoms.UnitVectors 7.101262720 0.0000000000 0.0000000000 0.0000000000 2.4600000381 0.0000000000 0.0000000000 0.0000000000 1 3.3999996185 Atoms.UnitVectors> However, in the NEGF calculation, the output file ‘UCell’ is not a square any more, and the ‘std’ file outputs the same. Namely, the original a axis has been changed, which can be confirmed by ‘cif’ output file. I wonder in this condition, what’s the real transport direction? Besides, this calculation got convergent after 8000 steps. I attach ‘std’, ‘UCell’ and ‘dat’ file for reference. Thank you very much for your help! Yours Sincerely, ZHOU Jiaqi ‘std’ file: <Check_System> The system is slab. lattice vectors (bohr) A = 40.258725274487, 0.000000000000, 6.425067640238 B = 0.000000000000, 4.648726003903, 0.000000000000 C = 0.000000000000, 0.000000000000, 25.322327526027 reciprocal lattice vectors (bohr^-1) RA = 0.156070150367, 0.000000000000, 0.000000000000 RB = -0.000000000000, 1.351592952974, 0.000000000000 RC = -0.039599885583, 0.000000000000, 0.248128269438 ‘UCell’ file Cell_Volume = 4739.118747914826 (Bohr^3) GridVol = 0.016791095337 (Bohr^3) Cell vectors (bohr) of the grid cell (gtv) gtv_a = 0.251617032966, 0.000000000000, 0.040156672751 gtv_b = 0.000000000000, 0.258262555772, 0.000000000000 gtv_c = 0.000000000000, 0.000000000000, 0.258391097204 |gtv_a| = 0.254801274810 |gtv_b| = 0.258262555772 |gtv_c| = 0.258391097204 ‘dat’ file # # File Name # System.CurrrentDirectory ./ # default=./ System.Name bilayer level.of.stdout 1 # default=1 (1-3) level.of.fileout 1 # default=1 (0-2) DATA.PATH ../DFT_DATA13 NEGF.filename.hks.l ../left-lead/left-lead.hks NEGF.filename.hks.r ../right-lead/right-lead.hks NEGF.SCF.Iter.Band 20 #NEGF.Num.Poles 100 # defalut=150 NEGF.scf.Kgrid 11 1 # defalut=1 1 # # Transmission & Eigen Channel Analysis # NEGF.tran.Analysis on # default on #NEGF.tran.energydiv 201 # default=200 NEGF.tran.energyrange -1 1 0.001 # default=-10.0 10.0 5.0e-3 (eV) NEGF.tran.Kgrid 100 1 # default= 1 1 NEGF.tran.CurrentDensity off # default on NEGF.tran.Channel off # default on # # Definition of Atomic Species # Species.Number 1 <Definition.of.Atomic.Species C C7.0-s1p1 C_PBE13 Definition.of.Atomic.Species> # # Atoms # Atoms.SpeciesAndCoordinates.Unit Ang # Ang|AU Atoms.Number 13 <Atoms.SpeciesAndCoordinates 1 C 7.101262720 0.000000000 0.000000000 2.0 2.0 2 C 7.811538259 1.230000019 3.3999996185 2.0 2.0 3 C 8.521600469 0.000000000 0.000000000 2.0 2.0 4 C 10.652000427 1.230000019 0.000000000 2.0 2.0 5 C 8.521600469 0.000000000 3.3999996185 2.0 2.0 6 C 10.652000427 1.230000019 3.3999996185 2.0 2.0 7 C 9.231662678 1.230000019 0.000000000 2.0 2.0 8 C 11.362063272 0.000000000 0.000000000 2.0 2.0 9 C 9.941938218 0.000000000 3.3999996185 2.0 2.0 10 C 12.072338176 1.230000019 3.3999996185 2.0 2.0 11 C 12.782401021 0.000000000 0.000000000 2.0 2.0 12 C 12.782401021 0.000000000 3.3999996185 2.0 2.0 13 C 13.492462595 1.230000019 0.000000000 2.0 2.0 Atoms.SpeciesAndCoordinates> Atoms.UnitVectors.Unit Ang # Ang|AU #<Atoms.UnitVectors # 8.521600469 0.0000000000 0.0000000000 # 0.0000000000 2.4600000381 0.0000000000 # 0.0000000000 0.0000000000 13.3999996185 #Atoms.UnitVectors> # # Lead-Left # LeftLeadAtoms.Number 7 <LeftLeadAtoms.SpeciesAndCoordinates # Unit=Ang. 1 C 0.000000000 0.000000000 0.000000000 2.0 2.0 2 C 2.130400117 1.230000019 0.000000000 2.0 2.0 3 C 0.710062368 1.230000019 0.000000000 2.0 2.0 4 C 2.840462486 0.000000000 0.000000000 2.0 2.0 5 C 4.260800234 0.000000000 0.000000000 2.0 2.0 6 C 6.391200510 1.230000019 0.000000000 2.0 2.0 7 C 4.970862444 1.230000019 0.000000000 2.0 2.0 LeftLeadAtoms.SpeciesAndCoordinates> # # Lead-Right # RightLeadAtoms.Number 7 <RightLeadAtoms.SpeciesAndCoordinates # Unit=Ang. 1 C 14.202738769 1.230000019 3.3999996185 2.0 2.0 2 C 14.912801137 0.000000000 3.3999996185 2.0 2.0 3 C 16.333138886 1.230000019 3.3999996185 2.0 2.0 4 C 17.043201255 0.000000000 3.3999996185 2.0 2.0 5 C 18.463539003 1.230000019 3.3999996185 2.0 2.0 6 C 19.173601213 0.000000000 3.3999996185 2.0 2.0 7 C 20.593939279 1.230000019 3.3999996185 2.0 2.0 RightLeadAtoms.SpeciesAndCoordinates> # # SCF or Electronic System # scf.XcType GGA-PBE # LDA|LSDA-CA|LSDA-PW|GGA-PBE scf.SpinPolarization off # On|Off|NC scf.ElectronicTemperature 300.0 # default=300 (K) #scf.energycutoff 200.0 # default=150 (Ry) #scf.Ngrid 140 140 100 # about=200 (Ry) scf.maxIter 10000 # default=40 scf.EigenvalueSolver NEGF # DC|GDC|Cluster|Band scf.lapack.dste dstevx # dstegr|dstedc|dstevx, default=dstegr scf.Kgrid 1 11 1 # means n1 x n2 x n3 scf.Mixing.Type Kerker # Simple|Rmm-Diis|Gr-Pulay|Kerker|Rmm-Diisk scf.Kerker.factor 20.0 # default=1 scf.Init.Mixing.Weight 0.05 # default=0.30 scf.Min.Mixing.Weight 0.005 # default=0.001 scf.Max.Mixing.Weight 0.2 # 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-7 # default=1.0e-6 (Hartree) # # MD or Geometry Optimization # MD.Type Nomd # Opt|EF|BFGS|RF|DIIS MD.Opt.DIIS.History 10 # default=3 MD.Opt.StartDIIS 6 # default=5 MD.Opt.EveryDIIS 5 # default=10 MD.maxIter 200 # MD.Opt.criterion 1.0e-4 # default=1.0e-4 (a.u.)

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