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NEGF Convergence problem in Magnetic junction
Date: 2014/06/05 18:03
Name: Umar   <umarfarooqphysics@gmail.com>

dear sir,
first of all thanks for helping me in CN case i am quite successful in calculating I-V curve up to .5 V for spin dependent case with uour help
I am working on Ni-Gr-Co (Ni-C-Co) system as Ni and Co are magnetic material i have a problem that i am unable to set the mixing parameters to get convergence state even at zero bias for NEGF calculation from many days i tried many options
but still system not seems to b converging pleas if any body expert can help me


this is my input file


DATA.PATH /home01/x936ufr/DATA/x865far/openmx/openmx3.7/DFT_DATA13
System.Name ngf-0.0
level.of.stdout 1 # default=1 (1-3)
level.of.fileout 0 # default=1 (0-2)


#
# Definition of Atomic Species
#

Species.Number 3
<Definition.of.Atomic.Species
C C5.0-s2p2 C_PBE13
Co Co6.0S-s2p3d2f1 Co_PBE13S
Ni Ni6.0S-s3p3d2f1 Ni_PBE13S
Definition.of.Atomic.Species>

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

NEGF.Num.Poles 100 # defalut=150
NEGF.scf.Kgrid 5 9 # 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)

NEGF.scf.Iter.Band 20
NEGF.Output.for.TranMain on

Dos.fileout on # on|off, default=off
NEGF.Dos.energyrange -10.0 10.0 1.0e-5 #default=-10.0 10.0 5.0e-3 (eV)
NEGF.Dos.energy.div 1000 # default=200
NEGF.Dos.Kgrid 5 9 # default=1 1

NEGF.tran.energydiv 2000 # default=200
NEGF.tran.energyrange -5.0 5.0 0.00001 # default=-10.0 10.0 5.0e-3 (eV)
NEGF.tran.Kgrid 5 9 # default= 1 1

Atoms.Number 12
Atoms.SpeciesAndCoordinates.Unit Ang # Ang|AU
<Atoms.SpeciesAndCoordinates
1 Co 6.23146 1.15757 0.28924 8.0 7.0
2 Co 6.23146 3.32785 1.54224 8.0 7.0
3 Co 8.27753 4.05176 0.28924 8.0 7.0
4 Co 8.27753 1.88100 1.54224 8.0 7.0
5 C 10.45632 4.05176 0.28924 2.0 2.0
6 C 10.45632 1.88100 1.54224 2.0 2.0
7 C 10.69010 0.43419 1.54224 2.0 2.0
8 C 10.69010 2.60443 0.28924 2.0 2.0
9 Ni 12.76487 0.43419 1.54224 9.0 7.0
10 Ni 12.76487 2.60443 0.28924 9.0 7.0
11 Ni 14.79954 4.05176 1.12457 9.0 7.0
12 Ni 14.79954 1.88100 2.37757 9.0 7.0
Atoms.SpeciesAndCoordinates>
Atoms.UnitVectors.Unit Ang # Ang|AU
LeftLeadAtoms.Number 6
<LeftLeadAtoms.SpeciesAndCoordinates # Unit=Ang.
1 Co 0.09305 1.15757 0.28924 8.0 7.0
2 Co 0.09305 3.32785 1.54224 8.0 7.0
3 Co 2.13912 4.05176 0.28924 8.0 7.0
4 Co 2.13912 1.88100 1.54224 8.0 7.0
5 Co 4.18518 0.43419 1.54224 8.0 7.0
6 Co 4.18518 2.60443 0.28924 8.0 7.0
LeftLeadAtoms.SpeciesAndCoordinates>


#
# Lead-Right
#
RightLeadAtoms.Number 6
<RightLeadAtoms.SpeciesAndCoordinates # Unit=Ang.
1 Ni 16.83421 1.15757 1.95992 9.0 7.0
2 Ni 16.83421 3.32785 0.70692 9.0 7.0
3 Ni 18.86868 0.43419 1.54224 9.0 7.0
4 Ni 18.86868 2.60443 0.28924 9.0 7.0
5 Ni 20.90335 4.05176 1.12457 9.0 7.0
6 Ni 20.90335 1.88100 2.37757 9.0 7.0
RightLeadAtoms.SpeciesAndCoordinates>

#
# SCF or Electronic System
#

scf.XcType GGA-PBE # LDA|LSDA-CA|LSDA-PW|GGA-PBE
scf.SpinPolarization on # On|Off|NC
scf.ElectronicTemperature 300.0 # default=300 (K)
scf.energycutoff 300.0 # default=150 (Ry)
#scf.Ngrid 20 20 20
scf.maxIter 1000 # default=40
scf.EigenvalueSolver NEGF # DC|GDC|Cluster|Band
scf.Kgrid 1 5 9 # means n1 x n2 x n3
scf.ProExpn.VNA off # default=on
scf.lapack.dste dstevx # dstegr|dstedc|dstevx,
scf.Mixing.Type Rmm-Diisk # Simple|Rmm-Diis|Gr-Pulay|Kerker|Rmm-Diisk
scf.Init.Mixing.Weight 0.1 # default=0.30
scf.Min.Mixing.Weight 0.001 # default=0.001
scf.Max.Mixing.Weight 0.200 # default=0.40
#scf.Kerker.factor 1.0 # default=1.0
scf.Mixing.History 40 # default=5
scf.Mixing.StartPulay 100 # default=6
scf.Mixing.EveryPulay 1 # default=5
scf.criterion 1.0e-8 # default=1.0e-6 (Hartree)


#
# MD or Geometry Optimization
#

MD.Type Nomd # Opt|EF|BFGS|RF|DIIS
MD.Opt.DIIS.History 18 # default=3
MD.Opt.StartDIIS 6 # default=5
MD.Opt.EveryDIIS 5 # default=10
MD.maxIter 1 #
MD.Opt.criterion 1.0e-4 # default=1.0e-4 (a.u.)

scf.restart off # on |off,default=off
memory.usage.fileout off # default=off, on|off


this is convenience history of 169
<DFT> NormRD = 1.000000000000 Criterion = 0.000000010000
<DFT> NormRD = 15.544667201474 Criterion = 0.000000010000
<DFT> NormRD = 15.452863930667 Criterion = 0.000000010000
<DFT> NormRD = 4.423670479750 Criterion = 0.000000010000
<DFT> NormRD = 5.376247514846 Criterion = 0.000000010000
<DFT> NormRD = 2.466995149482 Criterion = 0.000000010000
<DFT> NormRD = 2.474215954346 Criterion = 0.000000010000
<DFT> NormRD = 2.235780823113 Criterion = 0.000000010000
<DFT> NormRD = 1.923837897720 Criterion = 0.000000010000
<DFT> NormRD = 2.829665794904 Criterion = 0.000000010000
<DFT> NormRD = 1.722877009164 Criterion = 0.000000010000
<DFT> NormRD = 3.987464234412 Criterion = 0.000000010000
<DFT> NormRD = 3.382835797778 Criterion = 0.000000010000
<DFT> NormRD = 1.702500768126 Criterion = 0.000000010000
<DFT> NormRD = 3.480447558874 Criterion = 0.000000010000
<DFT> NormRD = 2.918766406687 Criterion = 0.000000010000
<DFT> NormRD = 1.561531428924 Criterion = 0.000000010000
<DFT> NormRD = 2.931618362876 Criterion = 0.000000010000
<DFT> NormRD = 2.274527799976 Criterion = 0.000000010000
<DFT> NormRD = 1.698980486826 Criterion = 0.000000010000
<DFT> NormRD = 10.629960163753 Criterion = 0.000000010000
<DFT> NormRD = 9.501514700856 Criterion = 0.000000010000
<DFT> NormRD = 3.640465302511 Criterion = 0.000000010000
.......................................................................
.............................................................
<DFT> NormRD = 5.165015233549 Criterion = 0.000000010000
<DFT> NormRD = 5.084396492414 Criterion = 0.000000010000
<DFT> NormRD = 12.290219502999 Criterion = 0.000000010000
<DFT> NormRD = 12.040737035039 Criterion = 0.000000010000
<DFT> NormRD = 31.667610546369 Criterion = 0.000000010000

<DFT> NormRD = 4.661888646311 Criterion = 0.000000010000
<DFT> NormRD = 3.557343344126 Criterion = 0.000000010000
<DFT> NormRD = 3.765797455171 Criterion = 0.000000010000
<DFT> NormRD = 3.453448799765 Criterion = 0.000000010000
<DFT> NormRD = 4.825448005765 Criterion = 0.000000010000
<DFT> NormRD = 4.826676816454 Criterion = 0.000000010000
<DFT> NormRD = 3.405802764337 Criterion = 0.000000010000
<DFT> NormRD = 3.857111587233 Criterion = 0.000000010000
<DFT> NormRD = 3.330457607994 Criterion = 0.000000010000
<DFT> NormRD = 3.899615396581 Criterion = 0.000000010000
<DFT> NormRD = 3.392977482105 Criterion = 0.000000010000
<DFT> NormRD = 9.389616267405 Criterion = 0.000000010000
<DFT> NormRD = 3.141486956609 Criterion = 0.000000010000
<DFT> NormRD = 3.145378732695 Criterion = 0.000000010000
<DFT> NormRD = 3.138637237874 Criterion = 0.000000010000
..................................................................
................................................................
<DFT> NormRD = 3.512996672054 Criterion = 0.000000010000
<DFT> NormRD = 4.265723250161 Criterion = 0.000000010000
<DFT> NormRD = 3.041081454845 Criterion = 0.000000010000
<DFT> NormRD = 3.096646323657 Criterion = 0.000000010000
<DFT> NormRD = 3.038930958966 Criterion = 0.000000010000
<DFT> NormRD = 3.280054663938 Criterion = 0.000000010000
<DFT> NormRD = 5.392795779915 Criterion = 0.000000010000
<DFT> NormRD = 4.182100894036 Criterion = 0.000000010000
<DFT> NormRD = 5.769913583183 Criterion = 0.000000010000
<DFT> NormRD = 3.536979036935 Criterion = 0.000000010000
<DFT> NormRD = 22.664704080420 Criterion = 0.000000010000
<DFT> NormRD = 21.849814674319 Criterion = 0.000000010000
<DFT> NormRD = 42.462142151388 Criterion = 0.000000010000
<DFT> NormRD = 33.658032937104 Criterion = 0.000000010000
<DFT> NormRD = 30.908378300367 Criterion = 0.000000010000
<DFT> NormRD = 20.986578371722 Criterion = 0.000000010000
<DFT> NormRD = 19.056858228722 Criterion = 0.000000010000
<DFT> NormRD = 19.161424820933 Criterion = 0.000000010000
<DFT> NormRD = 19.787601355136 Criterion = 0.000000010000
<DFT> NormRD = 20.515736568349 Criterion = 0.000000010000
<DFT> NormRD = 34.869777964504 Criterion = 0.000000010000
<DFT> NormRD = 36.950793447497 Criterion = 0.000000010000
<DFT> NormRD = 37.758007162316 Criterion = 0.000000010000
<DFT> NormRD = 41.603710261492 Criterion = 0.000000010000
<DFT> NormRD = 41.524392171618 Criterion = 0.000000010000
<DFT> NormRD = 35.839381185535 Criterion = 0.000000010000
<DFT> NormRD = 32.079235286096 Criterion = 0.000000010000
<DFT> NormRD = 31.478009133670 Criterion = 0.000000010000
<DFT> NormRD = 31.319980248151 Criterion = 0.000000010000
<DFT> NormRD = 31.230269886819 Criterion = 0.000000010000
<DFT> NormRD = 29.895483120669 Criterion = 0.000000010000
<DFT> NormRD = 29.993446224278 Criterion = 0.000000010000
<DFT> NormRD = 29.963014792296 Criterion = 0.000000010000
<DFT> NormRD = 29.828515711944 Criterion = 0.000000010000
<DFT> NormRD = 18.674823877089 Criterion = 0.000000010000
<DFT> NormRD = 15.259386102930 Criterion = 0.000000010000
<DFT> NormRD = 14.720470021904 Criterion = 0.000000010000
<DFT> NormRD = 14.489433793459 Criterion = 0.000000010000
<DFT> NormRD = 12.875125765097 Criterion = 0.000000010000
<DFT> NormRD = 12.932340783600 Criterion = 0.000000010000
<DFT> NormRD = 12.936540075093 Criterion = 0.000000010000
<DFT> NormRD = 12.270916282712 Criterion = 0.000000010000
<DFT> NormRD = 12.198925365640 Criterion = 0.000000010000
<DFT> NormRD = 12.068643473900 Criterion = 0.000000010000
<DFT> NormRD = 12.204059850264 Criterion = 0.000000010000
<
<DFT> NormRD = 8.558571709496 Criterion = 0.000000010000
<DFT> NormRD = 9.509660922528 Criterion = 0.000000010000
<DFT> NormRD = 9.586102911765 Criterion = 0.000000010000
<DFT> NormRD = 9.740108505816 Criterion = 0.000000010000
<DFT> NormRD = 10.158475552593 Criterion = 0.000000010000
<DFT> NormRD = 10.312862735676 Criterion = 0.000000010000
<DFT> NormRD = 13.593096355583 Criterion = 0.000000010000
<DFT> NormRD = 12.400681432659 Criterion = 0.000000010000
<DFT>
<DFT> NormRD = 7.335617102022 Criterion = 0.000000010000
<DFT> NormRD = 7.825062021195 Criterion = 0.000000010000
<DFT> NormRD = 6.498180031605 Criterion = 0.000000010000
<DFT> NormRD = 7.309121011752 Criterion = 0.000000010000
<DFT> NormRD = 7.169154420000 Criterion = 0.000000010000
<DFT> NormRD = 7.168729588428 Criterion = 0.000000010000
<DFT> NormRD = 8.445302288929 Criterion = 0.000000010000

if you can suggest me some tips
i will be very thankful to you

umar


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Re: NEGF Convergence problem in Magnetic junction ( No.1 )
Date: 2014/06/06 21:10
Name: Artem  <artem.pulkin@epfl.ch>

First of all, you have a problem with first 20 "periodic" iterations. Since they are very cheap I would suggest you to increase NEGF.scf.Iter.Band and to try to reach convergence there. Also it does not look like you relaxed your structures.

At this point, it is not a problem of NEGF calculations.
メンテ
Re: NEGF Convergence problem in Magnetic junction ( No.2 )
Date: 2014/06/09 21:57
Name: Umar   <umarfarooqphysics@gmail.com>

Dear Artem,

After trying on your tips. I am writing here .. I tried NEGF.scf.Iter.Band up to 300 it did not converge there also I also tried with higher range of mixing wait up to .6 but it did not work.
You are absolutely right about the I did not relaxed my structure on OpenMx but i am using structure relaxed on FLAP (full potential method) which is noticeably different.


even if it is not relaxed energy convergence should be achieved ? is it not possible on openmx ? is it helpful to use more no of orbital bases set ? or using making optimized bases set ? or any other way to converge it on this geometry ?
(because it is better for the constancy of the work )



any tip which can be helpful ?



thanks

Umar Farooq
メンテ
Re: NEGF Convergence problem in Magnetic junction ( No.3 )
Date: 2014/06/10 18:36
Name: Artem  <artem.pulkin@epfl.ch>

Your basis set is quite rich, I would say. Depending on the properties you are looking for, you may want to decrease it. In my research, I took the basis set which represents well the band structure of my material. It is usually enough if you study transport properties.

Try to switch to default Pulay parameters and decrease the basis size. I am not a specialist here but try for example

C C5.0-s2p2 C_PBE13
Co Co6.0S-s2p2d2 Co_PBE13S
Ni Ni6.0S-s2p2d2 Ni_PBE13S

And see if it works.
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