KPOINT BSE: Difference between revisions
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This allows calculating 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> \ | :<math> \mathbf{k} + n_{1} \mathbf{b}_{1}+ n_{2} \mathbf{b}_{2} + n_{3} \mathbf{b}_{3} </math> | ||
where <math>\ | where <math>\mathbf{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.|}} | {{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.|}} | ||
Latest revision as of 14:22, 14 October 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
- [math]\displaystyle{ \mathbf{k} + n_{1} \mathbf{b}_{1}+ n_{2} \mathbf{b}_{2} + n_{3} \mathbf{b}_{3} }[/math]
where [math]\displaystyle{ \mathbf{b}_{i} }[/math] 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. |