Supercell technique for total-energy calculations of finite charged and polar systems

TL;DR

This paper evaluates the supercell technique for total-energy calculations of finite charged and polar systems, demonstrating its accuracy and proposing improvements for finite-grid calculations.

Contribution

It introduces a cutoff Coulomb interaction within a plane-wave framework to accurately model finite charged and polar systems, assessing and improving supercell calculations.

Findings

Supercell method yields energies and structures close to finite system calculations.

Performance of finite-grid calculations can be enhanced with reciprocal space cutoff.

Supercell approach effectively handles large dipole moments in molecules.

Abstract

We study the behaviour of total-energy supercell calculations for dipolar molecules and charged clusters. Using a cutoff Coulomb interaction within the framework of a plane-wave basis set formalism, with all other aspects of the method (pseudopotentials, basis set, exchange-correlation functional) unchanged, we are able to assess directly the interaction effects present in the supercell technique. We find that the supercell method gives structures and energies in almost total agreement with the results of calculations for finite systems, even for molecules with large dipole moments. We also show that the performance of finite-grid calculations can be improved by allowing a degree of aliasing in the Hartree energy, and by using a reciprocal space definition of the cutoff Coulomb interaction.