Faster Exact Exchange in Periodic Systems using Single-precision Arithmetic
John T. Vinson
We show that the use of single-precision arithmetic for calculating the exchange interaction in periodic systems results in nearly halving computation time with only a negligible loss in accuracy. Density-functional theory simplifies many-electron calculations by treating the exchange and correlation interactions using a density functional. Hybrid functionals incorporate some amount of exact exchange, improving agreement with measured electronic and structural properties, but require more computer resources to carry out. Our implementation makes exact exchange calculations quicker and more feasible, especially for high- throughput calculations. We carry out example hybrid density-functional theory calculations of band energies, forces, and x-ray absorption spectra, and show that our single- precision implementation maintains accuracy with significantly reduced runtime and memory requirements.