Optimal finite-range atomic basis sets for liquid water and ice

TL;DR

This paper introduces a new scheme for generating finite-range atomic basis sets, demonstrating their high accuracy and transferability in modeling water and ice phases, comparable to high-cutoff plane-wave methods.

Contribution

The authors develop a series of high-accuracy finite-range basis sets for water, improving their generation process and validating their performance against plane-wave calculations.

Findings

Basis sets achieve plane-wave accuracy at ~1000 eV cutoff.

High transferability across different water phases.

Significantly improved total energy and pressure calculations.

Abstract

Finite-range numerical atomic orbitals are the basis functions of choice for several first principles methods, due to their flexibility and scalability. Generating and testing such basis sets, however, remains a significant challenge for the end user. We discuss these issues and present a new scheme for generating improved polarization orbitals of finite range. We then develop a series of high-accuracy basis sets for the water molecule, and report on their performance in describing the monomer and dimer, two phases of ice, and liquid water at ambient and high density. The tests are performed by comparison with plane-wave calculations, and show the atomic orbital basis sets to exhibit an excellent level of transferability and consistency. The highest-order bases (quadruple-zeta) are shown to give accuracies comparable to a plane-wave kinetic energy cutoff of at least ~1000 eV for quantities such as energy differences and ionic forces, as well as achieving significantly greater accuracies for total energies and absolute pressures.