Ab-initio calculation of phonon dispersion curves: accelerating q point convergence

TL;DR

This paper introduces a refined computational scheme for phonon dispersion calculations that enhances the accuracy of long-range interatomic force constants by using a non-uniform q point grid, improving convergence in density-functional perturbation theory.

Contribution

The authors propose a novel q point grid sampling method that accelerates convergence of phonon calculations, especially for long-range interactions, demonstrated on high-pressure silicon phases.

Findings

Improved convergence of phonon dispersion curves.

Enhanced accuracy in long-range force constant calculations.

Validated method on silicon high-pressure phases.

Abstract

We present a scheme for the improved description of the long-range interatomic force constants in a more accurate way than the procedure which is commonly used within plane-wave based density-functional perturbation-theory calculations. Our scheme is based on the inclusion of a q point grid which is denser in a restricted area around the center of the Brillouin Zone than in the remaining parts, even though the method is not limited to an area around Gamma. We have tested the validity of our procedure in the case of high-pressure phases of bulk silicon considering the bct and sh structure.