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NEGF calculations.
Date: 2018/02/22 18:17
Name: Hashmi   <arqumhashmi@gmail.com>

I am trying to calculate the NEGF calculations for Ni-Graphene-Ni junctions. I have several questions.First this is my input file.

NEGF.filename.hks.l left-lead.hks
NEGF.filename.hks.r right-lead.hks

NEGF.Num.Poles 150 # defalut=150
NEGF.scf.Kgrid 12 10 # defalut=1 1

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)

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 600 1 # default=1 1

NEGF.tran.CurrentDensity off # default on
NEGF.tran.Analysis off # default on
NEGF.tran.energydiv 200 # default=200
NEGF.tran.energyrange -10.0 10.0 1.0e-6 # default=-10.0 10.0 1.0e-3 (eV)
NEGF.tran.Kgrid 30 1 # default= 1 1
NEGF.tran.Channel off # default on
NEGF.Channel.Nkpoint 1 # default=1
<NEGF.Channel.kpoint
0.0 0.0
NEGF.Channel.kpoint>
# default 0.0 0.0
NEGF.Channel.Nenergy 1 # default=1
<NEGF.Channel.energy
0.0
NEGF.Channel.energy>
# default 0.0
NEGF.Channel.Num 5 # defualt=5(for collinear), 10(for Non-collinear)

#
# Definition of Atomic Species
#

Species.Number 2
<Definition.of.Atomic.Species
C C5.0-s2p2d1 C_PBE13
Ni Ni6.0S-s1p1d1 Ni_PBE13S
Definition.of.Atomic.Species>

#
# Atoms
#

Atoms.Number 28
Atoms.SpeciesAndCoordinates.Unit Ang # Ang|AU
<Atoms.SpeciesAndCoordinates
1 Ni 7.001194262 0.000000000 0.000000000 9 7
2 Ni 7.001194262 2.157959938 1.245900035 9 7
3 Ni 9.001194645 1.438668685 0.000000000 9 7
4 Ni 9.001194645 3.596628623 1.245900035 9 7
5 Ni 11.001195029 0.719334342 1.245900035 9 7
6 Ni 11.001195029 2.877294409 0.000000000 9 7
7 Ni 13.002003297 0.000000000 0.000000000 9 7
8 Ni 13.002003297 2.157959938 1.245900035 9 7
9 Ni 14.901992202 1.438668685 0.000000000 9 7
10 Ni 14.901992202 3.596628623 1.245900035 9 7
11 Ni 16.840817991 0.719334342 1.245900035 9 7
12 Ni 16.840817991 2.877294409 0.000000000 9 7
13 Ni 21.124012534 0.000000000 0.000000000 7 9
14 Ni 21.124012534 2.157959938 1.245900035 7 9
15 Ni 23.031613885 1.438668685 0.000000000 7 9
16 Ni 23.031613885 3.596628623 1.245900035 7 9
17 Ni 25.451193791 0.719334342 1.245900035 7 9
18 Ni 25.451193791 2.877294409 0.000000000 7 9
19 Ni 27.451194175 0.000000000 0.000000000 7 9
20 Ni 27.451194175 2.157959938 1.245900035 7 9
21 Ni 29.451194559 1.438668685 0.000000000 7 9
22 Ni 29.451194559 3.596628623 1.245900035 7 9
23 Ni 31.451197235 0.719334342 1.245900035 7 9
24 Ni 31.451197235 2.877294409 0.000000000 7 9
25 C 18.891611945 0.719334342 1.245900035 2.014 1.986
26 C 18.891611945 2.877294409 0.000000000 2.014 1.986
27 C 19.046416306 0.000000000 0.000000000 1.986 2.014
28 C 19.046416306 2.157959938 1.245900035 1.986 2.014
Atoms.SpeciesAndCoordinates>

LeftLeadAtoms.Number 6
<LeftLeadAtoms.SpeciesAndCoordinates # Unit=Ang.
1 Ni 1.00000000 0.000000000 0.000000000 9 7
2 Ni 1.00000000 2.157959938 1.245900035 9 7
3 Ni 3.00000000 1.438668685 0.000000000 9 7
4 Ni 3.00000000 3.596628623 1.245900035 9 7
5 Ni 5.00000000 0.719334342 1.245900035 9 7
6 Ni 5.00000000 2.877294409 0.000000000 9 7
LeftLeadAtoms.SpeciesAndCoordinates>

RightLeadAtoms.Number 6
<RightLeadAtoms.SpeciesAndCoordinates # Unit=Ang.
1 Ni 33.451197235 0.000000000 0.000000000 7 9
2 Ni 33.451197235 2.157959938 1.245900035 7 9
3 Ni 35.451197235 1.438668685 0.000000000 7 9
4 Ni 35.451197235 3.596628623 1.245900035 7 9
5 Ni 37.451197235 0.719334342 1.245900035 7 9
6 Ni 37.451197235 2.877294409 0.000000000 7 9
RightLeadAtoms.SpeciesAndCoordinates>

#Atoms.UnitVectors.Unit Ang # Ang|AU
#<Atoms.UnitVectors
# 36.450798191 0.0000000000 0.0000000000
# 0.0000000000 4.3159198761 0.0000000000
# 0.0000000000 0.0000000000 2.4918000698
#Atoms.UnitVectors>

# SCF or Electronic System
#
scf.XcType GGA-PBE # LDA|LSDA-CA|LSDA-PW|GGA-PBE
scf.SpinPolarization on # On|Off|NC
scf.ElectronicTemperature 600.0 # default=300 (K)
scf.energycutoff 200.0 # default=150 (Ry)
scf.EigenvalueSolver NEGF # DC|GDC|Cluster|Band
scf.Kgrid 1 12 10 # means n1 x n2 x n3
scf.Mixing.Type rmm-diisk # Simple|Rmm-Diis|Gr-Pulay|Kerker|Rmm-Diisk
scf.Init.Mixing.Weight 0.005 # 0.5 # default=0.30
scf.Mixing.History 401 # 100 default=5
scf.Mixing.EveryPulay 70 # 100 # default=1
scf.maxIter 6000 # default=40
scf.Min.Mixing.Weight 0.001 # 0.0001 # 0.08 # default=0.001
scf.Max.Mixing.Weight 0.40 # 0.05 # 0.7 default=0.40
scf.Mixing.StartPulay 80 # 90 default=6
scf.Kerker.factor 70.0 # 60 default=1
scf.criterion 1.0e-4 # default=1.0e-6 (Hartree)
scf.lapack.dste dstevx # dstevx|dstedc|dstegr,default=dstevx
NEGF.SCF.Iter.Band 0
scf.restart on


1- One is i have successfully converges the calculations upto 10-6 when the leads are FM. But with the same settings i am unable to converge with AFM leads even up to 10-4. Shouldn't same settings work on AFM leads??

2- Then i did a lot of effort (change parameters again and agian) and the calculation is almost converged upto 10-4 but job killed and when i restart the calculations again it didn't start from where it was finished and suddenly jumped to far away from that converged value and then takes a lot of time to reach to that convergence again?? Please explain it and how can i solve this problem. i have pasted screen shot of .DFTSCF file.

SCF= 2614 NormRD= 0.000024619606 Uele= 0.000000000000
SCF= 2615 NormRD= 0.000024331581 Uele= 0.000000000000
SCF= 2616 NormRD= 0.000024161712 Uele= 0.000000000000
SCF= 2617 NormRD= 0.000024014188 Uele= 0.000000000000
SCF= 2618 NormRD= 0.000023868946 Uele= 0.000000000000
SCF= 2619 NormRD= 0.000023725947 Uele= 0.000000000000
SCF= 2620 NormRD= 0.000023585154 Uele= 0.000000000000
SCF= 2621 NormRD= 0.000023446527 Uele= 0.000000000000
SCF= 2622 NormRD= 0.000023310033 Uele= 0.000000000000
SCF= 2623 NormRD= 0.000023175631 Uele= 0.000000000000
SCF= 2624 NormRD= 0.000023043287 Uele= 0.000000000000
SCF= 2625 NormRD= 0.000022912965 Uele= 0.000000000000
SCF= 2626 NormRD= 0.000022784629 Uele= 0.000000000000
SCF= 2627 NormRD= 0.000022658244 Uele= 0.000000000000
SCF= 2628 NormRD= 0.000022533776 Uele= 0.000000000000
SCF= 2629 NormRD= 0.000022411191 Uele= 0.000000000000
SCF= 2630 NormRD= 0.000022290454 Uele= 0.000000000000
SCF= 2631 NormRD= 0.000022171533 Uele= 0.000000000000
SCF= 2632 NormRD= 0.000022054396 Uele= 0.000000000000
SCF= 2633 NormRD= 0.000021939011 Uele= 0.000000000000
SCF= 2634 NormRD= 0.000021825345 Uele= 0.000000000000
SCF= 2635 NormRD= 0.000021713368 Uele= 0.000000000000

***********************************************************
***********************************************************
SCF history at MD= 1
***********************************************************
***********************************************************

SCF= 1 NormRD= 1.000000000000 Uele= 0.000000000000
SCF= 2 NormRD= 11.734904715922 Uele= 0.000000000000
SCF= 3 NormRD= 10.840914521379 Uele= 0.000000000000
SCF= 4 NormRD= 11.505686636553 Uele= 0.000000000000
SCF= 5 NormRD= 13.240369051547 Uele= 0.000000000000
SCF= 6 NormRD= 12.400031408157 Uele= 0.000000000000
SCF= 7 NormRD= 32.841439563738 Uele= 0.000000000000
SCF= 8 NormRD= 12.619717787668 Uele= 0.000000000000
SCF= 9 NormRD= 12.056009173628 Uele= 0.000000000000
SCF= 10 NormRD= 32.842025714310 Uele= 0.000000000000
SCF= 11 NormRD= 13.049119135518 Uele= 0.000000000000
SCF= 12 NormRD= 12.063356514925 Uele= 0.000000000000
SCF= 13 NormRD= 32.819628840100 Uele= 0.000000000000
SCF= 14 NormRD= 12.526472023578 Uele= 0.000000000000
SCF= 15 NormRD= 11.508819339663 Uele= 0.000000000000
SCF= 16 NormRD= 32.521066477303 Uele= 0.000000000000
SCF= 17 NormRD= 12.826905375792 Uele= 0.000000000000
SCF= 18 NormRD= 12.029392350442 Uele= 0.000000000000
SCF= 19 NormRD= 32.786421446865 Uele= 0.000000000000
SCF= 20 NormRD= 11.419064739337 Uele= 0.000000000000
SCF= 21 NormRD= 10.696988075546 Uele= 0.000000000000
SCF= 22 NormRD= 17.312726986263 Uele= 0.000000000000
SCF= 23 NormRD= 14.729318444858 Uele= 0.000000000000
SCF= 24 NormRD= 21.312907278056 Uele= 0.000000000000
SCF= 25 NormRD= 13.689252757207 Uele= 0.000000000000
SCF= 26 NormRD= 31.268500137808 Uele= 0.000000000000
SCF= 27 NormRD= 20.727126912333 Uele= 0.000000000000
SCF= 28 NormRD= 12.037777392030 Uele= 0.000000000000
SCF= 29 NormRD= 13.394562058711 Uele= 0.000000000000
SCF= 30 NormRD= 11.500679320957 Uele= 0.000000000000
SCF= 31 NormRD= 22.153273603121 Uele= 0.000000000000
SCF= 32 NormRD= 11.712654732292 Uele= 0.000000000000
SCF= 33 NormRD= 11.331335663364 Uele= 0.000000000000
SCF= 34 NormRD= 32.665284573423 Uele= 0.000000000000
SCF= 35 NormRD= 14.688989211462 Uele= 0.000000000000
SCF= 36 NormRD= 10.479928995703 Uele= 0.000000000000
SCF= 37 NormRD= 28.917877703285 Uele= 0.000000000000
SCF= 38 NormRD= 11.379830435401 Uele= 0.000000000000
SCF= 39 NormRD= 11.075381270889 Uele= 0.000000000000
SCF= 40 NormRD= 45.048530199021 Uele= 0.000000000000
SCF= 41 NormRD= 31.193945703511 Uele= 0.000000000000
SCF= 42 NormRD= 13.989518730783 Uele= 0.000000000000
SCF= 43 NormRD= 11.109583411002 Uele= 0.000000000000
SCF= 44 NormRD= 31.202389030667 Uele= 0.000000000000
SCF= 45 NormRD= 10.245332168097 Uele= 0.000000000000
SCF= 46 NormRD= 9.798777582193 Uele= 0.000000000000
SCF= 47 NormRD= 17.735739923043 Uele= 0.000000000000
SCF= 48 NormRD= 12.761362465314 Uele= 0.000000000000
SCF= 49 NormRD= 31.160494705599 Uele= 0.000000000000
SCF= 50 NormRD= 10.164692600379 Uele= 0.000000000000
SCF= 51 NormRD= 9.849802903980 Uele= 0.000000000000
SCF= 52 NormRD= 31.163912387372 Uele= 0.000000000000
SCF= 53 NormRD= 11.702398889602 Uele= 0.000000000000
SCF= 54 NormRD= 10.649761093856 Uele= 0.000000000000
SCF= 55 NormRD= 31.807385452424 Uele= 0.000000000000
SCF= 56 NormRD= 11.923205400800 Uele= 0.000000000000
SCF= 57 NormRD= 10.103177122650 Uele= 0.000000000000
SCF= 58 NormRD= 27.592854137876 Uele= 0.000000000000
SCF= 59 NormRD= 9.762102539418 Uele= 0.000000000000
SCF= 60 NormRD= 9.573029391972 Uele= 0.000000000000
SCF= 61 NormRD= 31.269141776585 Uele= 0.000000000000
SCF= 62 NormRD= 10.004060740082 Uele= 0.000000000000
SCF= 63 NormRD= 9.354902483154 Uele= 0.000000000000
SCF= 64 NormRD= 31.178861953124 Uele= 0.000000000000
SCF= 65 NormRD= 9.642375504236 Uele= 0.000000000000
SCF= 66 NormRD= 9.156673704175 Uele= 0.000000000000
SCF= 67 NormRD= 31.165084365731 Uele= 0.000000000000
SCF= 68 NormRD= 9.483128848131 Uele= 0.000000000000
SCF= 69 NormRD= 9.034463883554 Uele= 0.000000000000
SCF= 70 NormRD= 31.147670623379 Uele= 0.000000000000
SCF= 71 NormRD= 9.286908714281 Uele= 0.000000000000
SCF= 72 NormRD= 8.857526992166 Uele= 0.000000000000
SCF= 73 NormRD= 31.114467836730 Uele= 0.000000000000
SCF= 74 NormRD= 9.164795536972 Uele= 0.000000000000
SCF= 75 NormRD= 8.756653476430 Uele= 0.000000000000
SCF= 76 NormRD= 31.087839828091 Uele= 0.000000000000
SCF= 77 NormRD= 9.001774767533 Uele= 0.000000000000
SCF= 78 NormRD= 8.605395835424 Uele= 0.000000000000
SCF= 79 NormRD= 31.026601753430 Uele= 0.000000000000
SCF= 80 NormRD= 8.879891009912 Uele= 0.000000000000
SCF= 81 NormRD= 8.857620167191 Uele= 0.000000000000
SCF= 82 NormRD= 18.780564940039 Uele= 0.000000000000
SCF= 83 NormRD= 8.877515638560 Uele= 0.000000000000
SCF= 84 NormRD= 8.521065600241 Uele= 0.000000000000
SCF= 85 NormRD= 17.434560395097 Uele= 0.000000000000
SCF= 86 NormRD= 8.848751759091 Uele= 0.000000000000
SCF= 87 NormRD= 8.445755836023 Uele= 0.000000000000
SCF= 88 NormRD= 17.461696489223 Uele= 0.000000000000
SCF= 89 NormRD= 8.804516852018 Uele= 0.000000000000
SCF= 90 NormRD= 8.407450430690 Uele= 0.000000000000

メンテ
Page: [1]

Re: NEGF calculations. ( No.1 )
Date: 2018/02/23 18:51
Name: T. Ozaki

Hi,

> 1- One is i have successfully converges the calculations upto 10-6 when the leads are FM.
> But with the same settings i am unable to converge with AFM leads even up to 10-4.
> Shouldn't same settings work on AFM leads??

I think that the threshold of 1.0E-6 may be reached even for the AFM leads by tuning the
mixing parameters, since you have already reached to 1.0e-4.


> 2- Then i did a lot of effort (change parameters again and agian) and the calculation is
> almost converged upto 10-4 but job killed and when i restart the calculations again it
> didn't start from where it was finished and suddenly jumped to far away from that
> converged value and then takes a lot of time to reach to that convergence again?? Please
> explain it and how can i solve this problem. i have pasted screen shot of .DFTSCF file.

The restart files are saved after finishing the SCF loop. Therefore, if your calculation
is terminated during the SCF iteration, your second calculation cannot find any restart
files. This is what you encountered. If you can guess before calculation that your job
might be terminated by wall time, you should set a rather smaller scf.maxIter which guarantees
the normal end of the job, and restart again the job with the restart files.

Regards,

TO
メンテ
Re: NEGF calculations. ( No.2 )
Date: 2018/03/01 15:16
Name: Hashmi  <arqumhashmi@gmail.com>

Dear Sir,

Thank you very much for your prompt reply and your guidance.
I tried to calculate transport according to your suggestion. I have one question that i have set my criteria for the calculation is
scf.criterion 1.0e-5 # default=1.0e-6 (Hartree)

I have pasted the screenshot of .DFTSCF file. As you can see criteria has already been achieved from SCF= 278 but calculation is still running...... Can you explain it.??

SCF= 270 NormRD= 0.000011603228 Uele= 0.000000000000
SCF= 271 NormRD= 0.000011578918 Uele= 0.000000000000
SCF= 272 NormRD= 0.000011554969 Uele= 0.000000000000
SCF= 273 NormRD= 0.000054770300 Uele= 0.000000000000
SCF= 274 NormRD= 0.000052510751 Uele= 0.000000000000
SCF= 275 NormRD= 0.000046014720 Uele= 0.000000000000
SCF= 276 NormRD= 0.000030358660 Uele= 0.000000000000
SCF= 277 NormRD= 0.000012490034 Uele= 0.000000000000
SCF= 278 NormRD= 0.000006822217 Uele= 0.000000000000
SCF= 279 NormRD= 0.000006506257 Uele= 0.000000000000
SCF= 280 NormRD= 0.000006375016 Uele= 0.000000000000
SCF= 281 NormRD= 0.000006252835 Uele= 0.000000000000
SCF= 282 NormRD= 0.000006139219 Uele= 0.000000000000
SCF= 283 NormRD= 0.000006033692 Uele= 0.000000000000
SCF= 284 NormRD= 0.000005935785 Uele= 0.000000000000
SCF= 285 NormRD= 0.000005845047 Uele= 0.000000000000
SCF= 286 NormRD= 0.000005761038 Uele= 0.000000000000
SCF= 287 NormRD= 0.000005683333 Uele= 0.000000000000
SCF= 288 NormRD= 0.000005611525 Uele= 0.000000000000
SCF= 289 NormRD= 0.000005545223 Uele= 0.000000000000
SCF= 290 NormRD= 0.000005484049 Uele= 0.000000000000
SCF= 291 NormRD= 0.000005427643 Uele= 0.000000000000
メンテ
Re: NEGF calculations. ( No.3 )
Date: 2018/03/02 14:45
Name: T. Ozaki
References: t-ozaki@issp.u-tokyo.ac.jp

Hi,

For NEGF calculations, the termination condition is given by

sqrt(fabs(NormRD[0]))< scf.criterion

I see that your calculation seems to be convergent.
In such a case, you can stop the calculation by on-the-fly control
of SCF mixing parameters. Please take a look at
http://www.openmx-square.org/openmx_man3.8/node44.html

Regards,

TO

メンテ
Re: NEGF calculations. ( No.4 )
Date: 2018/03/05 11:31
Name: Hashmi  <arqumhashmi@gmail.com>

Dear Sir,
I have one more query. I have achieved convergence up to "scf.criterion 1.0e-5". But at the end of convergence i got strange results.

SCF= 485 NormRD= 0.000002560446 Uele= 0.000000000000
SCF= 486 NormRD= 0.000002155160 Uele= 0.000000000000
SCF= 487 NormRD= 0.000001818278 Uele= 0.000000000000
SCF= 488 NormRD= 0.000001538988 Uele= 0.000000000000
SCF= 489 NormRD= 0.000001308255 Uele= 0.000000000000
SCF= 490 NormRD= 0.000001118503 Uele= 0.000000000000
SCF= 491 NormRD= 0.000000963363 Uele= 0.000000000000

The leads are AFM (i have pasted my input before).
The magnetic moment intrinsic bias and the net bias at the end should be zero. But what i got is


Chemical potential of left lead (Hartree) -0.165363818129
Chemical potential of right lead (Hartree) -0.123022191185

***********************************************************
***********************************************************
Informaions for NEGF calculation
***********************************************************
***********************************************************


Intrinsic chemical potential (eV) of the leads
Left lead: -4.499778437490
Right lead: -3.347604146363
add voltage = 0.0000 (eV) to the left lead: new ChemP (eV): -4.4998
add voltage = 0.0000 (eV) to the right lead: new ChemP (eV): -3.3476

Intrinsic bias volatage: 1.152174291128 (eV)
Net bias volatage: 1.152174291128 (eV)

Parameters for the integration of the non-equilibrium part
lower bound: -5.453691291927 (eV)
upper bound: -2.393691291927 (eV)
energy step: 0.020000000000 (eV)
number of steps: 153

***********************************************************
***********************************************************
Mulliken populations
***********************************************************
***********************************************************

Total spin moment (muB) -4.189208324


Please comment on it. What went wrong?? How to rectify it....
メンテ
Re: NEGF calculations. ( No.5 )
Date: 2018/03/05 13:13
Name: T. Ozaki  <t-ozaki@issp.u-tokyo.ac.jp>

Hi,

When you calculated the following left and right leads by the band method,

left-lead.hks
right-lead.hks

did you check the chemical potentials for both the cases?
I wonder that you have the difference of chemical potentials in those calculations,
which may happen due to improper parameter setting such as different k-grids and
cutoff energy, etc.

Regards,

TO
メンテ

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