KPOINT BSE: Difference between revisions

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Description: {{TAG|KPOINT_BSE}}  specifies the k-point index at which VASP calculates the dielectric matrix.
Description: {{TAG|KPOINT_BSE}}  specifies the k-point index at which VASP calculates the dielectric matrix.
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In the simplest form one can specify
In the simplest form, one can specify


   KPOINT_BSE = index_of_k-point
   KPOINT_BSE = index_of_k-point
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   KPOINT_BSE = index_of_k-point  n1 n2 n3
   KPOINT_BSE = index_of_k-point  n1 n2 n3


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


:<math> \bold{k} + n_{1} \bold{b}_{1}+ n_{2} \bold{b}_{2} + n_{3} \bold{b}_{3} </math>
:<math> \bold{k} + n_{1} \bold{b}_{1}+ n_{2} \bold{b}_{2} + n_{3} \bold{b}_{3} </math>


where <math>\bold{b}_{i}</math> are the reciprocal-lattice vectors of the unit cell.
where <math>\bold{b}_{i}</math> are the reciprocal-lattice vectors of the unit cell.
{{NB|warning|We strongly recommend using {{TAG|ANTIRES}}{{=}}2 for the finite wavevector calculations. The Tamm-Dancoff approximation can lead to unphysical results for the dielectric function at a finite wavevector.|}}


== Related tags and articles ==
== Related tags and articles ==

Latest revision as of 17:02, 5 February 2025

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

Description: KPOINT_BSE specifies the k-point index at which VASP calculates the dielectric matrix.


In the simplest form, one can specify

  KPOINT_BSE = index_of_k-point

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 calculating the dielectric function at a k point outside of the first Brillouin zone corresponding to

where are the reciprocal-lattice vectors of the unit cell.

Warning: We strongly recommend using ANTIRES=2 for the finite wavevector calculations. The Tamm-Dancoff approximation can lead to unphysical results for the dielectric function at a finite wavevector.

Related tags and articles

BSE calculations

Examples that use this tag