Dear all, I increased the length of my electrodes further (by 50 percent), as Nick correctly pointed out, and the difference between Qtot and Qsol disappeared at low biases until 1 Volt. After that my transiesta still converges but a difference of about 0.5 to 0.65 becomes present at 1.8 Volt. Is it OK? What should I do to remove this difference? Is it necessary for me, in terms of validity of my currents, to try to remove this difference?
Regarding the above-mentioned convergence procedure for Qtot, is it OK that I do it at zero bias or I should do it at a different bias? Does the choice of basis, SZP or DZP, make any difference in the converged value of Qtot? Bests, Mohammad, On 10/1/15, Seyed Mohammad Tabatabaei <[email protected]> wrote: > Thank you very much. I misused width. I should have said length > instead. Thanks again. > > On 10/1/15, Nick Papior <[email protected]> wrote: >> add additional screening electrode layers, the length of the screening >> electrode layers. (not width, nor buffer) >> >> 2015-10-01 11:39 GMT+02:00 Seyed Mohammad Tabatabaei <[email protected]>: >> >>> Thank you very much. Do you mean I should add buffer layers or I must >>> only increase the width of my electrodes further? >>> >>> On 10/1/15, Nick Papior <[email protected]> wrote: >>> > You may have a longer ranging screening length of your electrode. >>> > >>> > Try and add more electrode layers. Generally you just want dQ to be as >>> low >>> > as possible, but sometimes it can be hard. >>> > >>> > See answer below: >>> > >>> > 2015-10-01 11:04 GMT+02:00 Seyed Mohammad Tabatabaei >>> > <[email protected]>: >>> > >>> >> Dear all, >>> >> >>> >> I have attached the three last steps of my transiesta convergence at >>> >> 0 >>> >> Volts bias. Even at this bias, there exists a difference beween Qsol >>> >> and Qtot. >>> >> >>> >> Is this difference which is equal to 0.337 tolerable? >>> >> >>> >> Is there any method to assess the maximum tolerable difference in my >>> >> calculation? Does it cause my calculated currents to become invalid >>> >> or >>> >> in any case the convergence is reached, the currents are valid? >>> >> >>> >> I have read many previous threads about this on the forum. In case my >>> >> questions are answered in some threads, I would be really grateful if >>> >> someone send the links. >>> >> >>> >> TranSiesta: Qsol,Qtot: 1008.337 1008.000 1.000 >>> >> transiesta: 20 -49567.1342 -49567.1262 -49567.1262 0.0003 >>> -3.0035 >>> >> TranSiesta: Qsol,Qtot: 1008.338 1008.000 1.000 >>> >> transiesta: 21 -49567.1436 -49567.1348 -49567.1348 0.0002 >>> -3.0035 >>> >> TranSiesta: Qsol,Qtot: 1008.339 1008.000 1.000 >>> >> transiesta: 22 -49567.1335 -49567.1341 -49567.1341 0.0001 >>> -3.0035 >>> >> TranSiesta: Qsol,Qtot: 1008.339 1008.000 1.000 >>> >> transiesta: 23 -49567.1320 -49567.1330 -49567.1330 0.0001 >>> -3.0035 >>> >> >>> >> One other critical question for me is that how should I know my Qtot >>> >> is correct? The parameters below are used in my calculation. The >>> >> width >>> >> of my electrodes are about 11 Angstroms which guarantees nearest >>> >> neighbor only interactions. Is it correct that I increase the >>> >> TS.ComplexContour.NPoles, TS.ComplexContour.NCircle, >>> >> TS.ComplexContour.NLine, and TS.biasContour.NumPoints all by one and >>> >> see if Qtot is still equal to 1008.000? Is this what is called >>> >> convergence test? >>> >> >>> > Yes. >>> > And adding more electrode layers can/is also part of the convergence >>> test. >>> > >>> >> >>> >> Best wishes, >>> >> Mohammad, >>> >> >>> >> SystemName scat >>> >> SystemLabel scat >>> >> %block kgrid_Monkhorst_Pack >>> >> 6 0 0 0.0 >>> >> 0 1 0 0.0 >>> >> 0 0 3 0.0 >>> >> %endblock kgrid_Monkhorst_Pack >>> >> xc.functional GGA >>> >> xc.authors PBE >>> >> MeshCutoff 300.0 Ry >>> >> SolutionMethod transiesta >>> >> OccupationFunction MP >>> >> ElectronicTemperature 300 K >>> >> MaxSCFIterations 300 >>> >> DM.NumberPulay 6 >>> >> DM.NumberBroyden 0 >>> >> DM.MixingWeight 0.1000000000 >>> >> DM.OccupancyTolerance 0.1000000000E-11 >>> >> DM.NumberKick 0 >>> >> DM.KickMixingWeight 0.5000000000 >>> >> DM.Tolerance 0.1000000000E-03 >>> >> UseSaveData T >>> >> DM.UseSaveDM T >>> >> ON.UseSaveLWF T >>> >> MD.UseSaveXV T >>> >> MD.UseSaveCG T >>> >> MD.NumCGsteps 0 >>> >> MD.TypeOfRun CG >>> >> MD.VariableCell F >>> >> MD.MaxCGDispl 0.2000000000 Bohr >>> >> MD.MaxForceTol 0.02 eV/Ang >>> >> PAO.SplitNorm 0.15392 >>> >> PAO.BasisSize DZP >>> >> %include POSITIONS.fdf >>> >> # transiesta information >>> >> TS.MixH T >>> >> # 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.BiasContour.Eta 0.000001 Ry >>> >> # TS OPTIONS >>> >> TS.Voltage 0.0 eV >>> >> # TBT OPTIONS >>> >> TS.TBT.Emin -3 eV >>> >> TS.TBT.Emax +3 eV >>> >> TS.TBT.NPoints 500 >>> >> TS.TBT.NEigen 3 >>> >> TS.TBT.Eta 0.000001 Ry >>> >> # Write electrode hamiltonian >>> >> TS.SaveHS .true. >>> >> TS.SaveLead .true. >>> >> # LEFT ELECTRODE >>> >> TS.HSFileLeft ./elec.TSHS >>> >> TS.NumUsedAtomsLeft 48 >>> >> TS.BufferAtomsLeft 0 >>> >> # RIGHT ELECTRODE >>> >> TS.HSFileRight ./elec.TSHS >>> >> TS.NumUsedAtomsRight 48 >>> >> TS.BufferAtomsRight 0 >>> >> >>> > >>> > >>> > >>> > -- >>> > Kind regards Nick >>> > >>> >> >> >> >> -- >> Kind regards Nick >> >
