On the accurate reproduction of strongly repulsive interatomic potentials

TL;DR

This paper demonstrates that a recent computational method can accurately reproduce strongly repulsive interatomic potentials at small internuclear distances, overcoming limitations of traditional electronic structure approaches.

Contribution

The study validates a new procedure for calculating repulsive potential energy curves at small R, enabling accurate results where standard methods fail.

Findings

Accurate reproduction of $V(R)$ at small R using the new method.

Comparison with numerical reference values confirms the method's reliability.

Applicable to multiple nuclear reactions involving noble gases and metals.

Abstract

Knowledge of the repulsive behavior of potential energy curves $V(R)$ at $R\to0$ is necessary for understanding and modeling irradiation processes of practical interest. $V(R)$ is in principle straightforward to obtain from electronic structure calculations; however, commonly-used numerical approaches for electronic structure calculations break down in the strongly repulsive region due to the closeness of the nuclei. In the present work, we show by comparison to fully numerical reference values that a recently developed procedure [S. Lehtola, J. Chem. Phys. 151, 241102 (2019)] can be employed to enable accurate linear combination of atomic orbitals calculations of $V(R)$ even at small $R$ by a study of the seven nuclear reactions He2 <=> Be, HeNe <=> Mg, Ne2 <=> Ca, HeAr <=> Ca, MgAr <=> Zn, Ar2 <=> Kr, and NeCa <=> Zn.