Ultrasoft pseudopotentials with kinetic energy density support: implementing the modified Becke-Johnson potential

TL;DR

This paper extends ultrasoft pseudopotentials with kinetic energy density support to enable the use of meta-GGA exchange potentials like Becke-Johnson in planewave DFT calculations, improving accuracy for electronic structure modeling.

Contribution

It introduces a method to incorporate kinetic energy density terms into ultrasoft pseudopotentials, allowing the use of advanced meta-GGA exchange potentials in planewave DFT implementations.

Findings

Validated the approach against all-electron benchmarks for atoms and semiconductors.

Provided practical guidelines for using Tran-Blaha exchange in pseudopotential codes.

Enhanced the accuracy of electronic structure calculations with meta-GGA potentials.

Abstract

We extend the Vanderbilt ultrasoft pseudopotential scheme by adding kinetic energy density terms, in order to use meta-GGA exchange potentials, such as the Becke-Johnson or Tran-Blaha potentials, in the planewave-pseudopotential implementation of Density Functional Theory. Having implemented kinetic energy augmentation and non-linear core correction terms in the CASTEP density functional package, we evaluate the validity of our approach by comparing the calculated electronic structure of isolated atoms and semiconductor crystals to all-electron benchmark calculations. Based on our results, we provide recommendations for the practical use of the Tran-Blaha exchange in planewave-pseudopotential codes.