Crystalline nickel

This example explains how to perform the density of states and band structure analyses by using crystalline nickel (Ni) as an example.

SCF calculation

We begin with an SCF calculation. We also perform the PDOS calculation at the convergence. Input file looks like:

TASK          SCF
WF_OPT        DAV
NTYP          1
NATM          1
TYPE          2
NSPG          225
GMAX           5.00
GMAXP         15.00
KPOINT_MESH   24 24 24
KPOINT_SHIFT  F     F     F
MIX_ALPHA     0.3
BZINT         TETRA
EDELTA        0.5000D-09
NSPIN         2
NEG           24
CELL          6.70 6.70 6.70  90.00  90.00  90.00
&INITIAL_ZETA
 0.200
&END
&ATOMIC_SPECIES
 Ni  58.690000 pot.Ni_pbe4
&END
&ATOMIC_COORDINATES CRYSTAL
  0.00  0.00  0.00    1    0    1
&END
&PDOS
 NPDOSAO 1
 IPDOST  1
 EMIN    -15.00
 EMAX      5.00
 EWIDTH    0.10
 NPDOSE   501
 RCUT    2.40
 RWIDTH  0.20
&END

We use the tetrahedron method for the Brillouin zone integration.

The total density of states printed to dos.data can be visualized as:

Band structure calculation

As in the Ag case, set:

TASK BAND

after the SCF calculation is converged and run the calculation. The input file for the band structure may look like:

TASK          BAND
WF_OPT        DAV
NTYP          1
NATM          1
TYPE          2
NSPG          225
GMAX           5.00
GMAXP         15.00
MIX_ALPHA     0.3
BZINT         TETRA
EDELTA        0.5000D-09
NSPIN         2
NEG           24
CELL          6.70 6.70 6.70  90.00  90.00  90.00
&INITIAL_ZETA
 0.200
&END
&ATOMIC_SPECIES
 Ni  58.690000 pot.Ni_pbe4
&END
&ATOMIC_COORDINATES CRYSTAL
  0.00  0.00  0.00    1    0    1
&END
&KPOINTS_BAND
 NKSEG 4
 KMESH 40 20 20 20
 KPOINTS
 0.000 0.000 0.000
 0.000 0.500 0.500
 0.250 0.500 0.750
 0.500 0.500 0.500
 0.000 0.000 0.000
&END

At the convergence, we obtain energy.data in addition to the standard output files. To convert the energy.data file into a plottable one, use energy2band program. For the spin polarized system (NSPIN=2), use

$ energy2band -s

Enter the number of bands, number of k-points (for the band structure calculation), and the energy origin (we use the Fermi level obtained in the SCF calculation or the valence band maximum), we obtain the band.data file. The band can be visualized by using gnuplot as: