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magnetic property of zigzag MoS2 nanoribbon
Date: 2015/11/04 22:52
Name: Will

Dear all,

When I was calculating the magnetic property of zigzag MoS2 nanoribbon, I set all the Mo atoms to be spin up, but it finally turned into a non-magnetic state, which, according to reference, is not true. (J. AM. CHEM. SOC. 2008, 130, 16739–16744)

My input file is attached.

#
# File Name
#

System.CurrrentDirectory ./ # default=./
System.Name MoS2-nanoribbon
level.of.stdout 1 # default=1 (1-3)
level.of.fileout 1 # default=1 (0-2)
DATA.PATH /home/fanchem/software/openmx3.7/DFT_DATA13
#
# Definition of Atomic Species
#

Species.Number 2
<Definition.of.Atomic.Species
S S7.0-s3p3d2f1 S_PBE13
Mo Mo7.0-s3p2d2f1 Mo_PBE13
Definition.of.Atomic.Species>

#
# Atoms
#

Atoms.Number 15
Atoms.SpeciesAndCoordinates.Unit Frac # Ang|AU
<Atoms.SpeciesAndCoordinates
1 S 2.1505163568867562 1.3725409648635019 0.7123029546705916 3.0 3.0
2 S 2.1504499788771025 1.3725440761757122 0.9244285172882953 3.0 3.0
3 S 2.6504525406774393 1.2639898766515452 0.7123029546705917 3.0 3.0
4 S 2.6503861626677860 1.2639929879637553 0.9244285172882955 3.0 3.0
5 S 2.1505163568867549 1.5896431412874152 0.7123029546705916 3.0 3.0
6 S 2.1504499788771025 1.5896462525996256 0.9244285172882953 3.0 3.0
7 S 2.6504525406774380 1.4810920530754585 0.7123029546705917 3.0 3.0
8 S 2.6503861626677860 1.4810951643876689 0.9244285172882955 3.0 3.0
9 S 2.6504525406774380 1.6981942294993724 0.7123029546705917 3.0 3.0
10 S 2.6503861626677856 1.6981973408115822 0.9244285172882955 3.0 3.0
11 Mo 2.1504847610674731 1.2278089672414034 0.8183615811316121 14.0 0.0
12 Mo 2.1504847610674731 1.4449111436653173 0.8183615811316121 14.0 0.0
13 Mo 2.6504209448581566 1.3363600554533606 0.8183615811316122 14.0 0.0
14 Mo 2.1504847610674731 1.6620133200892306 0.8183615811316121 14.0 0.0
15 Mo 2.6504209448581566 1.5534622318772744 0.8183615811316122 14.0 0.0
Atoms.SpeciesAndCoordinates>
Atoms.UnitVectors.Unit Ang # Ang|AU
<Atoms.UnitVectors
3.134000000000000 -0.000000000000002 0.000000000000000
0.000000000000000 25.000000000000000 0.000000000000000
0.000000000000000 0.000000000000000 15.000000000000000
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 300.0 # default=300 (K)
scf.energycutoff 200.0 # default=150 (Ry)
scf.maxIter 50 # default=40
scf.EigenvalueSolver band # DC|GDC|Cluster|Band
scf.Kgrid 21 1 1 # means n1 x n2 x n3
scf.Mixing.Type rmm-diis # Simple|Rmm-Diis|Gr-Pulay|Kerker|Rmm-Diisk
scf.Init.Mixing.Weight 0.30 # default=0.30
scf.Min.Mixing.Weight 0.001 # default=0.001
scf.Max.Mixing.Weight 0.400 # default=0.40
scf.Mixing.History 20 # default=5
scf.Mixing.StartPulay 15 # default=6
scf.criterion 1.0e-7 # default=1.0e-6 (Hartree)
scf.lapack.dste dstevx # dstevx|dstedc|dstegr,default=dstevx

#
# MD or Geometry Optimization
#

MD.Type BFGS # Nomd|Opt|NVE|NVT_VS|NVT_NH
# Constraint_Opt|DIIS
MD.maxIter 300 # default=1
MD.TimeStep 0.1 # default=0.5 (fs)
MD.Opt.criterion 1.0e-4 # default=1.0e-4 (Hartree/bohr)

Thank you!

Best wishes
Will
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Re: magnetic property of zigzag MoS2 nanoribbon ( No.1 )
Date: 2015/11/05 01:41
Name: Artem Pulkin

It is likely that you did not turn the spinorbit coupling on.

scf.spinorbit.coupling on
メンテ
Re: magnetic property of zigzag MoS2 nanoribbon ( No.2 )
Date: 2015/11/05 07:53
Name: Will

Here, I am just using scf.SpinPolarization on. Why do I need to use the spinorbit coupling in this case?

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Re: magnetic property of zigzag MoS2 nanoribbon ( No.3 )
Date: 2015/11/05 18:48
Name: Artem Pulkin

Why do you expect magnetic moments? Isn't it due to SOC in Mo?
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Re: magnetic property of zigzag MoS2 nanoribbon ( No.4 )
Date: 2015/11/05 22:54
Name: Will

No. In the reference, the authors also calculated the magnetic moments without considering SOC.
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Re: magnetic property of zigzag MoS2 nanoribbon ( No.5 )
Date: 2015/11/06 19:24
Name: Artem Pulkin

In that paper they do not mention spin-orbit coupling at all. What they do is they compare energies for spin-polarized (with SOC as far as I could see from the band structure) and spin-unpolarized calculations. Please correct me if I am wrong.
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Re: magnetic property of zigzag MoS2 nanoribbon ( No.6 )
Date: 2015/11/06 21:55
Name: Will

Yes, in the paper, they do not mention the spin-orbit coupling, then how can we imagine that the spin-polarized calculation is with SOC? Also, in Fig. 1 (c), the authors mentioned "Spatial spin distribution (up-down) of 8-ZMoS2NR", if they considered the SOC, can they still use up-down?

Thanks,
Will
メンテ
Re: magnetic property of zigzag MoS2 nanoribbon ( No.7 )
Date: 2015/11/07 00:35
Name: Artem Pulkin

Regarding your first question, no, I am not going to convince you any more that you should use SOC. If you have a question about the paper please ask the authors.

Regarding your second question, yes, the magnetic moments (or spins) may point up and down and any other direction. For a scalar-relativistic treatment they point up or down only (usually this means along z axis), in non-relativistic treatment there are no spins at all as far as I know.
メンテ

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