big forces of cubic SrTiO3 |
- Date: 2006/02/17 08:10
- Name: Sergey
Dear Dr. Ozaki,
I performed SCF calculations of simple perovskite - SrTiO3 in cubic unit cell, experimental parameters. But in ouput I see the large forces on the atoms. It is a little bit surpising for me because plane-wave calculations shows no forces on atoms during the same calculations. Probably, it is because that plane-wave codes use symmetry, so forces may be zero by symmetry. So, if it is true, is there a way how to avoid such big forces? My ouput file is here:
Thanks,
Sergey
#
# SCF calculation of a bulk diamond by the LDA and
# the band method
#
#
# File Name
#
System.CurrrentDirectory ./ # default=./
System.Name STO
level.of.stdout 1 # default=1 (1-3)
level.of.fileout 1 # default=1 (0-2)
#
# Definition of Atomic Species
#
Species.Number 3
<Definition.of.Atomic.Species
Sr Sr8.0-s3p2d1 Sr_LDA
Ti Ti7.0-s3p2d2 Ti_TM
O O5.0-s2p2d1 O_TM
Definition.of.Atomic.Species>
#
# Atoms
#
Atoms.Number 5
Atoms.SpeciesAndCoordinates.Unit AU # Ang|AU
<Atoms.SpeciesAndCoordinates
1 Sr 0.000 0.000 0.000 5.0 5.0
2 Ti 3.5 3.5 3.500 5.0 5.0
3 O 3.5 3.500 0.000 3.0 3.0
4 O 3.500 0.000 3.500 3.0 3.0
5 O 0.000 3.500 3.500 3.0 3.0
Atoms.SpeciesAndCoordinates>
Atoms.UnitVectors.Unit AU # Ang|AU
<Atoms.UnitVectors
7.3 0.0 0.0
0.0 7.3 0.0
0.0 0.0 7.3
Atoms.UnitVectors>
#
# SCF or Electronic System
#
scf.XcType LDA # LDA|LSDA-CA|LSDA-PW|GGA-PBE
scf.SpinPolarization off # On|Off|NC
scf.ElectronicTemperature 5.0 # default=300 (K)
scf.energycutoff 150.0 # default=150 (Ry)
scf.maxIter 100 # default=40
scf.EigenvalueSolver band # DC|GDC|Cluster|Band
scf.lapack.dste dstedc # dstegr|dstedc|dstevx, default=dstegr
scf.Kgrid 6 6 6 # means n1 x n2 x n3
scf.Mixing.Type rmm-diisk # 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 0.700 # default=0.40
scf.Mixing.History 7 # default=5
scf.Mixing.StartPulay 5 # default=6
scf.criterion 1.0e-7 # default=1.0e-6 (Hartree)
#
# 1D FFT
#
1DFFT.NumGridK 900 # default=900
1DFFT.NumGridR 900 # default=900
1DFFT.EnergyCutoff 3600.0 # default=3DFFT.EnergyCutoff*3.0 (Ry)
#
# Orbital Optimization
#
orbitalOpt.Method Off # Off|Unrestricted|Restricted
orbitalOpt.InitCoes Symmetrical # Symmetrical|Free
orbitalOpt.initPrefactor 0.1 # default=0.1
orbitalOpt.scf.maxIter 12 # default=12
orbitalOpt.MD.maxIter 2 # default=5
orbitalOpt.per.MDIter 2 # 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 3 # default=1
<Atoms.Cont.Orbitals
2
3
4
Atoms.Cont.Orbitals>
#
# SCF Order-N
#
orderN.HoppingRanges 4.0 # default=5.0 (Ang)
orderN.NumHoppings 1 # default=2
#
# MD or Geometry Optimization
#
MD.Type nomd # Nomd|Opt|NVE|NVT_VS|NVT_NH
MD.maxIter 1 # default=1
MD.TimeStep 1 # default=0.5 (fs)
MD.Opt.criterion 1.0e-5 # default=1.0e-4 (Hartree/bohr)
#
# Band dispersion
#
Band.dispersion off # on|off, default=off
<Band.KPath.UnitCell
3.56 0.00 0.00
0.00 3.56 0.00
0.00 0.00 3.56
Band.KPath.UnitCell>
# if <Band.KPath.UnitCell does not exist,
# the reciprical lattice vector is employed.
Band.Nkpath 2
<Band.kpath
15 0.0 0.0 0.0 1.0 0.0 0.0 g X
15 0.0 0.0 0.0 1.0 1.0 0.0 g X
Band.kpath>
#
# MO output
#
MO.fileout off # on|off
num.HOMOs 1 # default=2
num.LUMOs 1 # default=2
MO.Nkpoint 1 # default=1
<MO.kpoint
0.0 0.0 0.0
MO.kpoint>
#
# DOS and PDOS
#
Dos.fileout off # on|off, default=off
Dos.Erange -20.0 20.0 # default = -20 20
Dos.Kgrid 12 12 12 # default = Kgrid1 Kgrid2 Kgrid3
...
**********************************************************
***********************************************************
xyz-coordinates (Ang) and forces (Hartree/Bohr)
***********************************************************
***********************************************************
<coordinates.forces
5
1 Sr 0.00000 0.00000 0.00000 0.022964103457 0.022964103457 0.022964103457
2 Ti 1.85212 1.85212 1.85212 -0.001391846963 -0.001391846965 0.000044164545
3 O 1.85212 1.85212 0.00000 0.003717031049 0.003717031049 -0.028047250257
4 O 1.85212 0.00000 1.85212 0.002281019538 -0.028047250257 0.002281019539
5 O 0.00000 1.85212 1.85212 -0.028047250258 0.002281019538 0.002281019538
coordinates.forces>
...
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Re: big forces of cubic SrTiO3