Nanosurf Lab

to calculate the band structure for given lattice parameter we need to achieve SCF solution. Therefore we run a standard bulk calculation as described in previous chapter. Let's calculate the band structure for the lattice parameter alat = 5.5 Å, than the fireball.in file contains:

&OPTION
basisfile = Si.bas
lvsfile = Si.lvs
kptpreference = Si.kpts
nstepf = 1
rescal = 5.5
&END

where Si.bas, Si.lvs and Si.kpts files are identical as those used in previous chapter. Once we obtain the SCF solution, we run the FIREBALL code again, but now with fixed charges (ifixcharge = 1) and with a new set of k-points in desired high-symmetry directions in the first Brillouin zone. Remember we need having CHARGES file in a working directory for a restart. In this particular case,we have chosen a direction L-Γ-X-Γ stored in a lgxg.kpts file. In addition, we have to write out a list of eigenvalues at each k-point switching on iwrteigen variable.Our fireball.in file is now:

&OPTION
basisfile = Si.bas
lvsfile = Si.lvs
kptpreference = lgxg.kpts
nstepf = 1
ifixcharge = 1
rescal = 5.5
&END

&OUTPUT
iwrteigen = 1
&END