Faster Exact Exchange in Periodic Systems using Single-precision Arithmetic

TL;DR

This paper introduces a method to perform exact exchange calculations in periodic systems using single-precision arithmetic, significantly reducing computational time and memory while maintaining accuracy, thus enabling more efficient hybrid functional calculations.

Contribution

The authors develop a single-precision implementation for exact exchange in periodic systems, nearly halving computation time with negligible accuracy loss.

Findings

Calculation time reduced by nearly 50%.

Maintains accuracy in band energies, forces, and spectra.

Reduces memory requirements for hybrid functional calculations.

Abstract

Density-functional theory simplifies many-electron calculations by approximating the exchange and correlation interactions with a one-electron operator that is a functional of the density. Hybrid functionals incorporate some amount of exact exchange, improving agreement with measured electronic and structural properties. However, calculations with hybrid functionals require substantial computational resources, limiting their use. By calculating the exchange interaction of periodic systems with single-precision arithmetic, the computation time is cut nearly in half with a negligible loss in accuracy. This improvement makes exact exchange calculations quicker and more feasible, especially for high-throughput calculations. Example hybrid density-functional theory calculations of band energies, forces, and x-ray absorption spectra show that this single-precision implementation maintains accuracy with significantly reduced runtime and memory requirements.