Adaptively compressed exchange in LAPW

TL;DR

This paper introduces an implementation of the adaptively compressed exchange (ACE) operator within the LAPW method, enabling precise all-electron total-energy calculations with hybrid functionals and efficient gap predictions in solids.

Contribution

The paper presents a novel implementation of ACE in LAPW that maintains high precision in all-electron calculations with hybrid functionals, demonstrated on atoms, molecules, and solids.

Findings

ACE achieves high-precision total energies comparable to multi-resolution analysis.

High-energy local orbitals are crucial for accuracy in Fock exchange calculations.

The method accurately predicts PBE0 gaps in solids, aligning with other all-electron results.

Abstract

We present an implementation of the adaptively compressed exchange (ACE) operator in the LAPW formalism. ACE is a low-rank representation of the Fock exchange that avoids any loss of precision for the total energy. Our study shows that this property remains in the all-electron case, as we apply this method in non-relativistic total-energy calculations with a hybrid exchange-correlation functional PBE0. The obtained data for light atoms and molecules are within a few $\mu$Ha off the precise multi-resolution-analysis calculations. Aside from ACE, another key ingredient to achieve such a high precision with Fock exchange was the use of high-energy local orbitals. Finally, we use this implementation to calculate PBE0 gaps in solids and compare the results to other all-electron results.