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Bandstructure calculation for silicon

Here we will calculate the bandstructure of silicon. First step is to perform the scf calculation. Here is our input file:

src/silicon/silicon.in
# File Name
System.CurrrentDirectory  ./    # default=./
System.Name               silicon
DATA.PATH                 /home/svu/slspkd/openmx3.9/DFT_DATA19
level.of.stdout           1    # default=1 (1-3)
level.of.fileout          0    # default=1 (0-2)

# Definition of Atomic Species
Species.Number       1
<Definition.of.Atomic.Species
   Si   Si7.0-s2p2d1   Si_PBE19
Definition.of.Atomic.Species>

# Atoms
Atoms.Number         8
Atoms.SpeciesAndCoordinates.Unit   Ang # Ang|AU
<Atoms.SpeciesAndCoordinates           # Unit=Ang.
     1   Si   0.000000000000  0.000000000000  0.000000000000 2.0 2.0
     2   Si   0.000000000000  2.715000000000  2.715000000000 2.0 2.0
     3   Si   2.715000000000  0.000000000000  2.715000000000 2.0 2.0
     4   Si   2.715000000000  2.715000000000  0.000000000000 2.0 2.0
     5   Si   1.357500000000  1.357500000000  1.357500000000 2.0 2.0
     6   Si   1.357500000000  4.072500000000  4.072500000000 2.0 2.0
     7   Si   4.072500000000  1.357500000000  4.072500000000 2.0 2.0
     8   Si   4.072500000000  4.072500000000  1.357500000000 2.0 2.0
Atoms.SpeciesAndCoordinates>
Atoms.UnitVectors.Unit             Ang #  Ang|AU
<Atoms.UnitVectors                     # unit=Ang.
  5.430000000000  0.000000000000  0.000000000000
  0.000000000000  5.430000000000  0.000000000000
  0.000000000000  0.000000000000  5.430000000000
Atoms.UnitVectors>

# SCF or Electronic System
scf.XcType                 GGA-PBE     # LDA|LSDA-CA|LSDA-PW
scf.SpinPolarization       off         # On|Off
scf.ElectronicTemperature  300.0       # default=300 (K)
scf.energycutoff           160.0       # default=150 (Ry)
scf.maxIter                100         # default=40
scf.EigenvalueSolver       band        # Recursion|Cluster|Band
scf.lapack.dste            dstevx      # dstegr|dstedc|dstevx, default=dstegr
scf.Kgrid                  7 7 7       # means nk1xnk2xnk3
scf.Mixing.Type           rmm-diisk    # Simple|Rmm-Diis|Gr-Pulay
scf.Init.Mixing.Weight     0.010       # default=0.30
scf.Min.Mixing.Weight      0.001       # default=0.001
scf.Max.Mixing.Weight      0.200       # default=0.40
scf.Mixing.History         15          # default=5
scf.Mixing.StartPulay       5          # default=6
scf.criterion             1.0e-8       # default=1.0e-6 (Hartree)

Band.dispersion             on        # on|off, default=off
Band.Nkpath                  4
<Band.kpath
    20  0.0000 0.5000 0.0000   0.0000 0.0000 0.0000   L G
    30  0.0000 0.0000 0.0000   -0.500 0.0000 -0.500   G X
    10  -0.500 0.0000 -0.500   -0.375 0.2500 -0.375   X U
    30  -0.375 0.2500 -0.375   0.0000 0.0000 0.0000   U G
Band.kpath>

We can run the calculation using mpirun or submit via job-script:

mpirun -np 12 openmx silicon.in > silicon.out

While the calculation is running, you can monitor the convergence by:

grep "dUele" silicon.out | tail

Next step is to extract bandstructure data from silicon.Band file:

bandgnu13 silicon.Band

Finally, we can plot the bandstructure using gnuplot or any program of your choice:

gnuplot silicon.GNUBAND
silicon-band