Dissociation limit of the H2 molecule in the particle-hole random phase approximation

TL;DR

This paper demonstrates that the particle-hole random phase approximation accurately describes the dissociation limit of the H2 molecule, resolving a known challenge for density functional methods.

Contribution

We prove that the phRPA correlation energy is well-defined and correctly predicts the dissociation limit of H2, a notable achievement in electronic structure theory.

Findings

phRPA energy converges to twice the atomic value at dissociation

phRPA correlation energy is mathematically well-defined

Correct dissociation behavior for H2 in phRPA

Abstract

In this work, we consider the particle-hole random phase approximation (phRPA), an approximation to the correlation energy in electronic structure, and show that the phRPA energy of the H2 molecule correctly dissociates. That is, as the hydrogen atoms are pulled apart, the phRPA energy of the system converges to twice the phRPA energy of a single hydrogen atom. Despite the simplicity of the H2 system, the correct dissociation of H2 is known to be a difficult problem for density functional approximations. As part of our result, we prove that the phRPA correlation energy is well-defined.