Understanding failures in electronic structure methods arising from the geometric phase effect

• Main Authors: Kjønstad, Eirik F, Koch, Henrik
• Format: Journal Article
• Language: English
• Published: 12-11-2024
• Subjects: Physics - Chemical Physics
• DOI: 10.48550/arxiv.2411.08209

We show that intermediate normalization of the electronic wave function,
where a constant component is enforced, will lead to an asymptotic
discontinuity at one point along any path that encloses a ground state conical
intersection. For some electronic structure methods, this gives rise to severe
global artifacts in the ground and excited state potential energy surfaces. We
investigate how this affects two electronic structure methods: coupled cluster
theory and M{\o}ller-Plesset perturbation theory. The analysis suggests that
intermediate normalization is problematic not only in near-degenerate regions,
such as in the vicinity of conical intersections. In particular, since problems
will occur for any path that encloses a ground state intersection, the affected
methods can unexpectedly break down in regions of internal coordinate space
that are normally considered within their range of validity.