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# KPOINT BSE

KPOINT_BSE = [integer] (optionally [integer],[integer],[integer])

Descprition: The flag KPOINT_BSE allows to calculate the dielectric matrix at one of the kpoints used to sample the Brillouin zone.

In the simplest form one can specify

  KPOINT_BSE = index_of_k-point


It is best to select the desired k-point from the list of k-points in the OUTCAR file. Additionally a shift by an arbitrary reciprocal lattice vector can be supplied by specifying three additional integer numbers:

 KPOINT_BSE = index_of_k-point  n1 n2 n3


This allows the calculate the dielectric function at a k-point outside the first Brillouin zone corresponding to

${\displaystyle {\mathbf {k}}+n_{{1}}{\mathbf {b}}_{{1}}+n_{{2}}{\mathbf {b}}_{{2}}+n_{{3}}{\mathbf {b}}_{{3}}}$

where ${\displaystyle {\mathbf {b}}_{{i}}}$ are the reciprocal lattice vectors of the unit cell.