Curvilinear coordinates for full-core atoms

TL;DR

This paper introduces a curvilinear coordinate transformation that enables efficient and accurate electronic-structure calculations for full-core atoms, improving computational feasibility and reducing correlation times.

Contribution

It extends the use of curvilinear coordinates to full-core atomic systems, providing a practical method for plane-wave calculations and Monte Carlo simulations.

Findings

Achieved a 120 Ryd energy cutoff for carbon and silicon

Reduced correlation time in Monte Carlo calculations

Validated with tests on Li, C, and Si atoms

Abstract

Curvilinear coordinates, first introduced by F. Gygi for valence-only electronic systems within the local-density functional theory, can be used to describe both core and valence electrons in electronic-structure calculations. A simple and quite general coordinate transformation results in a large, yet affordable plane-wave energy cutoff for full-core systems (e.g., about 120 Ryd for carbon or silicon) within the local-density functional theory, and in a reduced correlation time for full-core variational Monte Carlo calculations. Numerical tests for isolated Li, C, and Si atoms are presented.