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problems in band dispersion
Date: 2011/08/12 19:42
Name: wsajad   <wsajad44@gmail.com>

Dear Dr. T.Ozaki and openmx users,

i am using openmx3.5 and want to calculate the band dispersion of PbTe in bulk phase.
i have generated vps and pao using adpack but i could not get the correct band structure for the semiconductor. as according my band dispersion the band gap is wide enough. my input file is as follows



Species.Number 2
<Definition.of.Atomic.Species
Pb Pb3_CA-s1p1d1 Pb3_CA
Te Te2_CA-s1p1d1 Te2_CA
Definition.of.Atomic.Species>

#
# Atoms
#

Atoms.Number 2
Atoms.SpeciesAndCoordinates.Unit Ang # Ang|AU
<Atoms.SpeciesAndCoordinates
1 Pb 0.500000 0.500000 0.500000 1.0 1.0
2 Te 0.000000 0.000000 0.000000 3.0 3.0
Atoms.SpeciesAndCoordinates>
Atoms.UnitVectors.Unit Ang # Ang|AU
<Atoms.UnitVectors
0.0000 3.2300 3.2300
3.2300 0.0000 3.2300
3.2300 3.2300 0.0000
Atoms.UnitVectors>

#
# SCF or Electronic System
#

scf.XcType LDA # LDA|LSDA-CA|LSDA-PW|GGA-PBE
scf.SpinPolarization off # On|Off|NC
scf.ElectronicTemperature 350.0 # default=300 (K)
scf.energycutoff 100.0 # default=150 (Ry)
scf.maxIter 60 # default=40
scf.EigenvalueSolver Band # DC|GDC|Cluster|Band
scf.Kgrid 6 6 6 # 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 7 # default=5
scf.Mixing.StartPulay 4 # default=6
scf.criterion 1.0e-8 # default=1.0e-6 (Hartree)
scf.lapack.dste dstevx # dstevx|dstedc|dstegr,default=dstevx

#
# 1D FFT
#

1DFFT.NumGridK 900 # default=900
1DFFT.NumGridR 900 # default=900
1DFFT.EnergyCutoff 2500.0 # default=3600 (Ry)

#
# Orbital Optimization
#

orbitalOpt.Method Restricted # Off|Unrestricted|Restricted
orbitalOpt.InitCoes Symmetrical # Symmetrical|Free
orbitalOpt.initPrefactor 0.1 # default=0.1
orbitalOpt.scf.maxIter 15 # default=12
orbitalOpt.MD.maxIter 7 # default=5
orbitalOpt.per.MDIter 20 # default=1000000
orbitalOpt.criterion 1.0e-4 # default=1.0e-4 (Hartree/borh)^2

#
# output of contracted orbitals
#

CntOrb.fileout off # on|off, default=off
Num.CntOrb.Atoms 1 # default=1
<Atoms.Cont.Orbitals
1
Atoms.Cont.Orbitals>

#
# SCF Order-N
#

orderN.HoppingRanges 6.0 # default=5.0 (Ang)
orderN.NumHoppings 2 # default=2

#
# MD or Geometry Optimization
#

MD.Type nomd # Nomd|Opt|DIIS|NVE|NVT_VS|NVT_NH# Nomd|Opt|DIIS|NVE|NVT_VS|NVT_NH
MD.Opt.DIIS.History 4 # default=7
MD.Opt.StartDIIS 5 # default=5
MD.maxIter 1 # default=1
MD.TimeStep 1.0 # default=0.5 (fs)
MD.Opt.criterion 1.0e-5 # default=1.0e-4 (Hartree/bohr)

#
# Band dispersion
#

Band.dispersion on # on|off, default=off
<Band.KPath.UnitCell
6.46000000 0.00000000 0.00000000
0.00000000 6.46000000 0.00000000
0.00000000 0.00000000 6.46000000
Band.KPath.UnitCell>
# if <Band.KPath.UnitCell does not exist,
# the reciprical lattice vector is employed.
Band.Nkpath 4
<Band.kpath
25 0.00 0.00 0.00 0.50 0.00 0.00 g X
25 0.50 0.00 0.00 0.50 0.25 0.00 X W
25 0.50 0.25 0.00 0.25 0.25 0.25 W L
25 0.25 0.25 0.25 0.00 0.00 0.00 L g
Band.kpath>

#
# restart using a restart file, *.rst
#

scf.restart off # on|off,default=off

#
# MO output
#

MO.fileout off # on|off
num.HOMOs 1 # default=1
num.LUMOs 1 # default=1
MO.Nkpoint 1 # default=1
<MO.kpoint
0.0 0.0 0.0
MO.kpoint>

#
# DOS and PDOS
#

Dos.fileout on # on|off, default=off
Dos.Erange -20 20 # default = -20 20
Dos.Kgrid 3 3 3 # default = Kgrid1 Kgrid2 Kgrid3

#
# output Hamiltonian and overlap
#

HS.fileout off # on|off, default=off





i have modified the no. of valence electrons in the default vps and pao too in some calculations but could not solve the problem..
so i request your good self to help me..
hope u ll reply this post soon
thanks
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Re: problems in band dispersion ( No.1 )
Date: 2011/09/02 07:45
Name: Julio Aguiar  <jaguiar@arn.gob.ar>

Hi

The PbTe is a FCC with an a=6.454 Angstrom
You can perform the test with the following input:

I recommend using the input data of Pb and Te from:

http://www.jaist.ac.jp/~t-ozaki/vps_pao2006/vps_pao.html

In the folder DFT_DATA for the following input

#
# Atoms
#

Atoms.Number 2
Atoms.SpeciesAndCoordinates.Unit FRAC # Ang|AU
<Atoms.SpeciesAndCoordinates
1 Pb 0.000000 0.000000 0.000000 10.0 10.0
2 Te 0.500000 0.500000 0.500000 8.0 8.0
Atoms.SpeciesAndCoordinates>
Atoms.UnitVectors.Unit Ang # Ang|AU
<Atoms.UnitVectors
3.2300 0.0000 0.0000
0.0000 3.2300 0.0000
0.0000 0.0000 3.2300
Atoms.UnitVectors>



メンテ
Re: problems in band dispersion ( No.2 )
Date: 2011/09/03 16:34
Name: wsajad  <wsajad44@gmail.com>

dear sir,
i have used almost all the possible combinations of pseudopotentials and pseudo atomic orbitals found in the data base. Sir unfortunately none leads to the desired band gap. A help in this regard will be most kindness..
thanks
メンテ
Re: problems in band dispersion ( No.3 )
Date: 2011/09/03 16:44
Name: Sajad Ahmad  <wsajad44@gmail.com>

I have already used the above.
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