Dear Liu, If I remember correctly the minimum voltage for transiesta is 0.1 V so the 0.02V and 0.05V make no sense (at least the 0.02V is actually calculated at 0V, 0.05V seems to be calculated at 0.1V but still doesn't explain the strange behavior there).
Another thing, I think you should at least have a SZP basis for reasonable results. Regards Henrik Den 17 april 2012 09:37 skrev liuyunlong0902 <[email protected]>: > Dear All, > Recently, I used transiesta to calculate some electrical > properties of graphene under conditions of different doping densities. The > channel length is 2nm and 8 carbon atoms are used as electrodes. Both the > channel and electrodes are confirmed in the same doping level. The > results are shown in the following figure. At bias=0.02V, the current is > zero, although the doping density is different. When bias is 0.2V or 1.0V, > the current is almost the same at low doping density. Whereas, if the bias > is set at 0.05V, I got a current curve increasing with the density at low > doping level. I also check the output files, both Siesta and Transiesta are > convergent. I am confused about which result is more reasonable? > > Best Regards, > Liu > > > > > > > The input files are attached : > ----------------------------------------------------------------- > SystemName scat > SystemLabel scat > %block kgrid_Monkhorst_Pack > 200 0 0 0.0 > 0 1 0 0.0 > 0 0 1 0.0 > %endblock kgrid_Monkhorst_Pack > xc.functional LDA > xc.authors CA > MeshCutoff 200.00000000 Ry > MaxSCFIterations 1000 > DM.NumberPulay 6 > DM.NumberBroyden 0 > DM.MixingWeight 0.05000000000 > DM.OccupancyTolerance 0.1000000000E-11 > DM.NumberKick 0 > DM.KickMixingWeight 0.5000000000 > DM.Tolerance 0.001 > UseSaveData T > MD.NumCGsteps 0 > MD.TypeOfRun Verlet > MD.VariableCell F > MD.MaxCGDispl 0.2000000000 Bohr > MD.MaxForceTol 0.05 eV/Ang > Diag.ParallelOverK F > PAO.EnergyShift 0.02 Ry > PAO.SplitNorm 0.1500000000 > PAO.BasisType split > %block PAO.BasisSizes > C SZ > %endblock PAO.BasisSizes > WriteMullikenPop 0 > WriteBands F > SaveRho F > SaveElectrostaticPotential F > SaveTotalPotential F > WriteCoorXmol T > > > NetCharge = -0.009432 (or -0.09432, -0.0009432 ……) > > %block ChemicalSpeciesLabel > 1 6 C > %endblock ChemicalSpeciesLabel > %include SPOSITIONS.fdf > # Transiesta information > SolutionMethod Transiesta > # GENGF OPTIONS > TS.ComplexContour.Emin -28 eV > TS.ComplexContour.NPoles 16 > TS.ComplexContour.NCircle 16 > TS.ComplexContour.NLine 10 > # BIAS OPTIONS > TS.biasContour.NumPoints 10 > # TS OPTIONS > TS.Voltage 0.05 eV > # TBT OPTIONS > TS.TBT.Emin -2 eV > TS.TBT.Emax +2 eV > TS.TBT.NPoints 200 > TS.TBT.NEigen 3 > TS.TBT.Eta 0.000001 Ry > # Write electrode hamiltonian > TS.SaveHS .true. > TS.SaveLead .true. > # LEFT ELECTRODE > TS.HSFileLeft ./Left-elec.TSHS > TS.NumUsedAtomsLeft 8 > TS.BufferAtomsLeft 0 > # RIGHT ELECTRODE > TS.HSFileRight ./Right-elec.TSHS > TS.NumUsedAtomsRight 8 > TS.BufferAtomsRight 0 > > > > >
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