problem with getting current in armchair MOS2 nanoribbon in transiesta

Asked by Samaneh Soleimani-Amiri on 2020-10-13

Dear all,

I am using transiesta code to get the I-V characteristics of Armchair MoS2 nanoribbon as scattering (with 8 unit cells) and electrode material. All the calculations (electrode, transiesta and tbtrans) run perfectly for the voltage range of 0-2V with good SCF convergence. However, in all voltages I get nearly zero transmission in the bias window and consequently very low current (about 10^-16 A).
Since my armchair MoS2 NR is a semiconductor with the bandgap of about 0.5 eV I expected that current should start to increase exponentially from 0.5 V bias and reach the order of micro Ampere. I have attached .fdf files of my scattering region.
I would appreciate if someone could help me to find the problem.

#1D System
############################
############################
SystemName nanoribbon
SystemLabel nanoribbon

##################
#Basis#
##################
PAO.BasisSize SZ # Default value
PAO.SplitNorm 0.15392 # I needed this only for MoS2. You can comment it.
##################

NumberOfAtoms 300
NumberOfSpecies 2

%block ChemicalSpeciesLabel
    1 42 Mo
    2 16 S
%endblock ChemicalSpeciesLabel

LatticeConstant 1 Ang
%block LatticeVectors
   30 0.000 0.000
   0.000 20 0.000
   0.000 0.000 55.434
%endblock LatticeVectors

AtomicCoordinatesFormat ScaledCartesian
%block AtomicCoordinatesAndAtomicSpecies
       1.8002228700 1.0003288500 0.9999338300 2
       1.8002242700 4.1946693600 0.9999332400 2
       3.4003340900 2.5974499300 1.9239275200 1
       5.0007030100 1.0002326100 1.0000988500 2
       5.0007014900 4.1947681000 1.0000959600 2
       6.6008540600 2.5974502400 1.9238950600 1
       8.2011900700 1.0002353700 1.0001004200 2
       8.2011896000 4.1947659500 1.0000972300 2
       9.8013327900 2.5974501100 1.9239004900 1
      11.4017032200 1.0002389000 1.0001055200 2
      11.4017032000 4.1947634700 1.0001014900 2
      13.0017952000 2.5974501300 1.9238913900 1
      14.6022591700 1.0002698100 1.0000806400 2
      14.6022572900 4.1947285500 1.0000791700 2
      16.2021642900 2.5974496000 1.9240037000 1

       1.8003562500 2.5974496400 4.6957038200 1
       3.4003023300 1.0002695000 3.7716814700 2
       3.4003024700 4.1947286100 3.7716793700 2
       5.0007057800 2.5974500500 4.6955913300 1
       6.6008475700 1.0002397200 3.7717062300 2
       6.6008474500 4.1947631700 3.7717015600 2
       8.2011877100 2.5974501600 4.6956004300 1
       9.8013298800 1.0002354100 3.7717009300 2
       9.8013296700 4.1947661200 3.7716977700 2
      11.4016965900 2.5974502600 4.6955953200 1
      13.0017981100 1.0002320300 3.7716990900 2
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      14.6022262500 2.5974499400 4.6956276500 1
      16.2022974000 1.0003288000 3.7715339900 2
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       5.0007030100 1.0002326100 6.5434989500 2
       5.0007014900 4.1947681000 6.5434960600 2
       6.6008540600 2.5974502400 7.4672951600 1
       8.2011900700 1.0002353700 6.5435005200 2
       8.2011896000 4.1947659500 6.5434973300 2
       9.8013327900 2.5974501100 7.4673005900 1
      11.4017032200 1.0002389000 6.5435056200 2
      11.4017032000 4.1947634700 6.5435015900 2
      13.0017952000 2.5974501300 7.4672914900 1
      14.6022591700 1.0002698100 6.5434807400 2
      14.6022572900 4.1947285500 6.5434792700 2
      16.2021642900 2.5974496000 7.4674038000 1

       1.8003562500 2.5974496400 10.2391039200 1
       3.4003023300 1.0002695000 9.3150815700 2
       3.4003024700 4.1947286100 9.3150794700 2
       5.0007057800 2.5974500500 10.2389914300 1
       6.6008475700 1.0002397200 9.3151063300 2
       6.6008474500 4.1947631700 9.3151016600 2
       8.2011877100 2.5974501600 10.2390005300 1
       9.8013298800 1.0002354100 9.3151010300 2
       9.8013296700 4.1947661200 9.3150978700 2
      11.4016965900 2.5974502600 10.2389954200 1
      13.0017981100 1.0002320300 9.3150991900 2
      13.0017989500 4.1947675300 9.3150970500 2
      14.6022262500 2.5974499400 10.2390277500 1
      16.2022974000 1.0003288000 9.3149340900 2
      16.2022962300 4.1946697500 9.3149339100 2

       1.8002228700 1.0003288500 12.0867340300 2
       1.8002242700 4.1946693600 12.0867334400 2
       3.4003340900 2.5974499300 13.0107277200 1
       5.0007030100 1.0002326100 12.0868990500 2
       5.0007014900 4.1947681000 12.0868961600 2
       6.6008540600 2.5974502400 13.0106952600 1
       8.2011900700 1.0002353700 12.0869006200 2
       8.2011896000 4.1947659500 12.0868974300 2
       9.8013327900 2.5974501100 13.0107006900 1
      11.4017032200 1.0002389000 12.0869057200 2
      11.4017032000 4.1947634700 12.0869016900 2
      13.0017952000 2.5974501300 13.0106915900 1
      14.6022591700 1.0002698100 12.0868808400 2
      14.6022572900 4.1947285500 12.0868793700 2
      16.2021642900 2.5974496000 13.0108039000 1

       1.8003562500 2.5974496400 15.7825040200 1
       3.4003023300 1.0002695000 14.8584816700 2
       3.4003024700 4.1947286100 14.8584795700 2
       5.0007057800 2.5974500500 15.7823915300 1
       6.6008475700 1.0002397200 14.8585064300 2
       6.6008474500 4.1947631700 14.8585017600 2
       8.2011877100 2.5974501600 15.7824006300 1
       9.8013298800 1.0002354100 14.8585011300 2
       9.8013296700 4.1947661200 14.8584979700 2
      11.4016965900 2.5974502600 15.7823955200 1
      13.0017981100 1.0002320300 14.8584992900 2
      13.0017989500 4.1947675300 14.8584971500 2
      14.6022262500 2.5974499400 15.7824278500 1
      16.2022974000 1.0003288000 14.8583341900 2
      16.2022962300 4.1946697500 14.8583340100 2

       1.8002228700 1.0003288500 17.6301341300 2
       1.8002242700 4.1946693600 17.6301335400 2
       3.4003340900 2.5974499300 18.5541278200 1
       5.0007030100 1.0002326100 17.6302991500 2
       5.0007014900 4.1947681000 17.6302962600 2
       6.6008540600 2.5974502400 18.5540953600 1
       8.2011900700 1.0002353700 17.6303007200 2
       8.2011896000 4.1947659500 17.6302975300 2
       9.8013327900 2.5974501100 18.5541007900 1
      11.4017032200 1.0002389000 17.6303058200 2
      11.4017032000 4.1947634700 17.6303017900 2
      13.0017952000 2.5974501300 18.5540916900 1
      14.6022591700 1.0002698100 17.6302809400 2
      14.6022572900 4.1947285500 17.6302794700 2
      16.2021642900 2.5974496000 18.5542040000 1

       1.8003562500 2.5974496400 21.3259041200 1
       3.4003023300 1.0002695000 20.4018817700 2
       3.4003024700 4.1947286100 20.4018796700 2
       5.0007057800 2.5974500500 21.3257916300 1
       6.6008475700 1.0002397200 20.4019065300 2
       6.6008474500 4.1947631700 20.4019018600 2
       8.2011877100 2.5974501600 21.3258007300 1
       9.8013298800 1.0002354100 20.4019012300 2
       9.8013296700 4.1947661200 20.4018980700 2
      11.4016965900 2.5974502600 21.3257956200 1
      13.0017981100 1.0002320300 20.4018993900 2
      13.0017989500 4.1947675300 20.4018972500 2
      14.6022262500 2.5974499400 21.3258279500 1
      16.2022974000 1.0003288000 20.4017342900 2
      16.2022962300 4.1946697500 20.4017341100 2

       1.8002228700 1.0003288500 23.1735342300 2
       1.8002242700 4.1946693600 23.1735336400 2
       3.4003340900 2.5974499300 24.0975279200 1
       5.0007030100 1.0002326100 23.1736992500 2
       5.0007014900 4.1947681000 23.1736963600 2
       6.6008540600 2.5974502400 24.0974954600 1
       8.2011900700 1.0002353700 23.1737008200 2
       8.2011896000 4.1947659500 23.1736976300 2
       9.8013327900 2.5974501100 24.0975008900 1
      11.4017032200 1.0002389000 23.1737059200 2
      11.4017032000 4.1947634700 23.1737018900 2
      13.0017952000 2.5974501300 24.0974917900 1
      14.6022591700 1.0002698100 23.1736810400 2
      14.6022572900 4.1947285500 23.1736795700 2
      16.2021642900 2.5974496000 24.0976041000 1

       1.8003562500 2.5974496400 26.8693042200 1
       3.4003023300 1.0002695000 25.9452818700 2
       3.4003024700 4.1947286100 25.9452797700 2
       5.0007057800 2.5974500500 26.8691917300 1
       6.6008475700 1.0002397200 25.9453066300 2
       6.6008474500 4.1947631700 25.9453019600 2
       8.2011877100 2.5974501600 26.8692008300 1
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      13.0017989500 4.1947675300 25.9452973500 2
      14.6022262500 2.5974499400 26.8692280500 1
      16.2022974000 1.0003288000 25.9451343900 2
      16.2022962300 4.1946697500 25.9451342100 2

       1.8002228700 1.0003288500 28.7169343300 2
       1.8002242700 4.1946693600 28.7169337400 2
       3.4003340900 2.5974499300 29.6409280200 1
       5.0007030100 1.0002326100 28.7170993500 2
       5.0007014900 4.1947681000 28.7170964600 2
       6.6008540600 2.5974502400 29.6408955600 1
       8.2011900700 1.0002353700 28.7171009200 2
       8.2011896000 4.1947659500 28.7170977300 2
       9.8013327900 2.5974501100 29.6409009900 1
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      13.0017952000 2.5974501300 29.6408918900 1
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      14.6022572900 4.1947285500 28.7170796700 2
      16.2021642900 2.5974496000 29.6410042000 1

       1.8003562500 2.5974496400 32.4127043200 1
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       3.4003024700 4.1947286100 31.4886798700 2
       5.0007057800 2.5974500500 32.4125918300 1
       6.6008475700 1.0002397200 31.4887067300 2
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       8.2011877100 2.5974501600 32.4126009300 1
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       9.8013296700 4.1947661200 31.4886982700 2
      11.4016965900 2.5974502600 32.4125958200 1
      13.0017981100 1.0002320300 31.4886995900 2
      13.0017989500 4.1947675300 31.4886974500 2
      14.6022262500 2.5974499400 32.4126281500 1
      16.2022974000 1.0003288000 31.4885344900 2
      16.2022962300 4.1946697500 31.4885343100 2

       1.8002228700 1.0003288500 34.2603344300 2
       1.8002242700 4.1946693600 34.2603338400 2
       3.4003340900 2.5974499300 35.1843281200 1
       5.0007030100 1.0002326100 34.2604994500 2
       5.0007014900 4.1947681000 34.2604965600 2
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       8.2011896000 4.1947659500 34.2604978300 2
       9.8013327900 2.5974501100 35.1843010900 1
      11.4017032200 1.0002389000 34.2605061200 2
      11.4017032000 4.1947634700 34.2605020900 2
      13.0017952000 2.5974501300 35.1842919900 1
      14.6022591700 1.0002698100 34.2604812400 2
      14.6022572900 4.1947285500 34.2604797700 2
      16.2021642900 2.5974496000 35.1844043000 1

       1.8003562500 2.5974496400 37.9561044200 1
       3.4003023300 1.0002695000 37.0320820700 2
       3.4003024700 4.1947286100 37.0320799700 2
       5.0007057800 2.5974500500 37.9559919300 1
       6.6008475700 1.0002397200 37.0321068300 2
       6.6008474500 4.1947631700 37.0321021600 2
       8.2011877100 2.5974501600 37.9560010300 1
       9.8013298800 1.0002354100 37.0321015300 2
       9.8013296700 4.1947661200 37.0320983700 2
      11.4016965900 2.5974502600 37.9559959200 1
      13.0017981100 1.0002320300 37.0320996900 2
      13.0017989500 4.1947675300 37.0320975500 2
      14.6022262500 2.5974499400 37.9560282500 1
      16.2022974000 1.0003288000 37.0319345900 2
      16.2022962300 4.1946697500 37.0319344100 2

       1.8002228700 1.0003288500 39.8037345300 2
       1.8002242700 4.1946693600 39.8037339400 2
       3.4003340900 2.5974499300 40.7277282200 1
       5.0007030100 1.0002326100 39.8038995500 2
       5.0007014900 4.1947681000 39.8038966600 2
       6.6008540600 2.5974502400 40.7276957600 1
       8.2011900700 1.0002353700 39.8039011200 2
       8.2011896000 4.1947659500 39.8038979300 2
       9.8013327900 2.5974501100 40.7277011900 1
      11.4017032200 1.0002389000 39.8039062200 2
      11.4017032000 4.1947634700 39.8039021900 2
      13.0017952000 2.5974501300 40.7276920900 1
      14.6022591700 1.0002698100 39.8038813400 2
      14.6022572900 4.1947285500 39.8038798700 2
      16.2021642900 2.5974496000 40.7278044000 1

       1.8003562500 2.5974496400 43.4995045200 1
       3.4003023300 1.0002695000 42.5754821700 2
       3.4003024700 4.1947286100 42.5754800700 2
       5.0007057800 2.5974500500 43.4993920300 1
       6.6008475700 1.0002397200 42.5755069300 2
       6.6008474500 4.1947631700 42.5755022600 2
       8.2011877100 2.5974501600 43.4994011300 1
       9.8013298800 1.0002354100 42.5755016300 2
       9.8013296700 4.1947661200 42.5754984700 2
      11.4016965900 2.5974502600 43.4993960200 1
      13.0017981100 1.0002320300 42.5754997900 2
      13.0017989500 4.1947675300 42.5754976500 2
      14.6022262500 2.5974499400 43.4994283500 1
      16.2022974000 1.0003288000 42.5753346900 2
      16.2022962300 4.1946697500 42.5753345100 2

       1.8002228700 1.0003288500 45.3471346300 2
       1.8002242700 4.1946693600 45.3471340400 2
       3.4003340900 2.5974499300 46.2711283200 1
       5.0007030100 1.0002326100 45.3472996500 2
       5.0007014900 4.1947681000 45.3472967600 2
       6.6008540600 2.5974502400 46.2710958600 1
       8.2011900700 1.0002353700 45.3473012200 2
       8.2011896000 4.1947659500 45.3472980300 2
       9.8013327900 2.5974501100 46.2711012900 1
      11.4017032200 1.0002389000 45.3473063200 2
      11.4017032000 4.1947634700 45.3473022900 2
      13.0017952000 2.5974501300 46.2710921900 1
      14.6022591700 1.0002698100 45.3472814400 2
      14.6022572900 4.1947285500 45.3472799700 2
      16.2021642900 2.5974496000 46.2712045000 1

       1.8003562500 2.5974496400 49.0429046200 1
       3.4003023300 1.0002695000 48.1188822700 2
       3.4003024700 4.1947286100 48.1188801700 2
       5.0007057800 2.5974500500 49.0427921300 1
       6.6008475700 1.0002397200 48.1189070300 2
       6.6008474500 4.1947631700 48.1189023600 2
       8.2011877100 2.5974501600 49.0428012300 1
       9.8013298800 1.0002354100 48.1189017300 2
       9.8013296700 4.1947661200 48.1188985700 2
      11.4016965900 2.5974502600 49.0427961200 1
      13.0017981100 1.0002320300 48.1188998900 2
      13.0017989500 4.1947675300 48.1188977500 2
      14.6022262500 2.5974499400 49.0428284500 1
      16.2022974000 1.0003288000 48.1187347900 2
      16.2022962300 4.1946697500 48.1187346100 2

       1.8002228700 1.0003288500 50.8905347300 2
       1.8002242700 4.1946693600 50.8905341400 2
       3.4003340900 2.5974499300 51.8145284200 1
       5.0007030100 1.0002326100 50.8906997500 2
       5.0007014900 4.1947681000 50.8906968600 2
       6.6008540600 2.5974502400 51.8144959600 1
       8.2011900700 1.0002353700 50.8907013200 2
       8.2011896000 4.1947659500 50.8906981300 2
       9.8013327900 2.5974501100 51.8145013900 1
      11.4017032200 1.0002389000 50.8907064200 2
      11.4017032000 4.1947634700 50.8907023900 2
      13.0017952000 2.5974501300 51.8144922900 1
      14.6022591700 1.0002698100 50.8906815400 2
      14.6022572900 4.1947285500 50.8906800700 2
      16.2021642900 2.5974496000 51.8146046000 1

       1.8003562500 2.5974496400 54.5863047200 1
       3.4003023300 1.0002695000 53.6622823700 2
       3.4003024700 4.1947286100 53.6622802700 2
       5.0007057800 2.5974500500 54.5861922300 1
       6.6008475700 1.0002397200 53.6623071300 2
       6.6008474500 4.1947631700 53.6623024600 2
       8.2011877100 2.5974501600 54.5862013300 1
       9.8013298800 1.0002354100 53.6623018300 2
       9.8013296700 4.1947661200 53.6622986700 2
      11.4016965900 2.5974502600 54.5861962200 1
      13.0017981100 1.0002320300 53.6622999900 2
      13.0017989500 4.1947675300 53.6622978500 2
      14.6022262500 2.5974499400 54.5862285500 1
      16.2022974000 1.0003288000 53.6621348900 2
      16.2022962300 4.1946697500 53.6621347100 2
%endblock AtomicCoordinatesAndAtomicSpecies

##################################
#Bandstructure k points# # Uncomment the following only when you want the bandstructure.
##################################
BandLinesScale ReciprocalLatticeVectors
%block BandLines
1 0.0 0.0 0.0
50 0.0 0.0 0.5
%endblock Bandlines

##################################
#Sampling k points 0D#
##################################
%block kgrid_Monkhorst_Pack # For DOS calculations use X3. More info on DOS calculation can be find at PDOS analysis section.
 1 0 0 0.0
 0 1 0 0.0
 0 0 100 0.0
%endblock kgrid_Monkhorst_pack

################
#DFT, Grid, SCF#
################

MeshCutoff 300. Ry

MaxSCFIterations 200
DM.MixingWeight 0.05
DM.NumberPulay 6
DM.NumberKick 5
DM.KickMixingWeight 0.20
DM.MixSCF1 F # Default value
DM.Tolerance 0.0001 # Default value
DM.InitSpinAF F # Default value (For SpinPolarized=T)
ElectronicTemperature 300 K

DM.UseSaveDM .true.
UseSaveData .true.

SpinPolarized .false.
XC.functional GGA
XC.authors PBE

WriteMullikenPop 1
SaveDeltaRho .true.
SaveRho .true.
SaveElectrostaticPotential .true.
SaveTotalPotential .true.

SolutionMethod transiesta

TS.WriteHS .true.
TS.NumUsedAtomsLeft 30
TS.NumUsedAtomsRight 30
TS.HSFileLeft './elec.TSHS'
TS.HSFileRight './elec.TSHS'
TS.TBT.HSFile './nanoribbon.TSHS'

TS.Voltage 0.7 eV
TS.biasContour.NumPoints 30
TS.biasContour.Eta 0.001 eV

TS.TBT.Emin -2.0 eV
TS.TBT.Emax 2.0 eV
TS.TBT.NPoints 400

Best regards,
Samaneh Soleimani-Amiri

Question information

Language:
English Edit question
Status:
Answered
For:
Siesta Edit question
Assignee:
No assignee Edit question
Last query:
2020-10-13
Last reply:
2020-10-13
Nick Papior (nickpapior) said : #1

Two things

1. Don't do DFT+NEGF calculations with semiconductor electrodes. There are too many pitfalls for this to actually work, in particular the screening for semi-conductors are very bad and thus your system needs to be extremely big for this to work.

2. Don't apply bias to pristine systems. If the electrons can't scatter, you can't build up a potential drop (i.e. you are forcing the system to do something unphysical!)

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