MP vs regular k-mesh - difference in band structure |
- Date: 2016/06/21 14:10
- Name: Eike F. Schwier
<schwier@hiroshima-u.ac.jp>
- Dear Ozaki-sensei,
I was trying to calculate the band structure of a single Fe(001) layer to get accustomed with the new unfolding method. After plotting the raw band structure (Band.dispersion on) I found that the bands along the G-X and G-Y lines exhibit slightly different dispersions as well as binding energies (most clearly seen in the band 0.2 eV above the fermi energy at the G-point). I checked different convergence parameter (cutoff, basis orbitals, k-mesh density, functional) as well as the versions 3.7.10 and 3.8.0, but finally found the only way to get the band structure symmetric was to change scf.Generation.Kpoint from MP to regular. That way I could get a symmetric dispersion of the bands.
Did I miss some input, or should I not use the MP?
For your convenience I have attached my input file below.
best regards,
Eike
#
# File Name
#
DATA.PATH /home/calc/src/openmx3.8/DFT_DATA13
System.CurrrentDirectory ./ # default=./
System.Name Fe001
level.of.stdout 1 # default=1 (1-3)
level.of.fileout 1 # default=1 (0-2)
#
#
# Definition of Atomic Species
#
Species.Number 1
<Definition.of.Atomic.Species
Fe Fe6.0S-s3p3d2f1 Fe_CA13S
Definition.of.Atomic.Species>
#
# Atoms
#
Atoms.Number 1
Atoms.SpeciesAndCoordinates.Unit FRAC # Ang|AU
<Atoms.SpeciesAndCoordinates
1 Fe 0 0 0 7 7
Atoms.SpeciesAndCoordinates>
Atoms.UnitVectors.Unit Ang # Ang|AU
<Atoms.UnitVectors
2.82740 0 0
0 2.82740 0
0 0 56.548
Atoms.UnitVectors>
#
# SCF or Electronic System
#
scf.XcType LSDA-CA # LDA|LSDA-CA|LSDA-PW|GGA-PBE
scf.SpinPolarization off # On|Off|NC
scf.SpinOrbit.Coupling off # On|Off, default=off
scf.ElectronicTemperature 1500.0 # default=300 (K)
scf.energycutoff 250.0 # default=150 (Ry)
scf.maxIter 450 # default=40
scf.EigenvalueSolver band # DC|GDC|Cluster|Band
scf.Kgrid 16 16 1 # means n1 x n2 x n3
scf.Generation.Kpoint MP # regular|MP
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 0.0001 # default=0.001
scf.Max.Mixing.Weight 0.11 # default=0.40
scf.Mixing.History 40 # default=5
scf.Mixing.StartPulay 35 # default=6
scf.Mixing.EveryPulay 1 # default=6
scf.criterion 1.0e-8 # default=1.0e-6 (Hartree)
scf.lapack.dste dstevx # dstevx|dstedc|dstegr,default=dstevx
#
# Band output
#
Band.dispersion on # on|off, default=off
# if <Band.KPath.UnitCell does not exist,
# the reciprical lattice vector is employed.
Band.Nkpath 2
<Band.kpath
150 0.5 0 0 0 0 0 X G
150 0 0 0 0 0.5 0 G Y
Band.kpath>
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Re: MP vs regular k-mesh - difference in band structure