Coupled cluster cavity Born-Oppenheimer approximation for electronic strong coupling

TL;DR

This paper investigates the cavity Born-Oppenheimer approximation's effectiveness in modeling strong light-matter interactions, comparing it with a polaritonic approach to understand electron-photon correlations in molecular complexes.

Contribution

It provides a detailed analysis of the CBOA's accuracy and limitations in describing intermolecular interactions under strong coupling conditions.

Findings

CBOA approximates potential energy surfaces well for certain molecular systems.

Electron-photon correlation effects are significant in strong coupling regimes.

Comparison with polaritonic approach highlights the strengths and weaknesses of CBOA.

Abstract

Chemical and photochemical reactivity, as well as supramolecular organization and several other molecular properties, can be modified by strong interactions between light and matter. Theoretical studies of these phenomena require the separation of the Schr\"odinger equation into different degrees of freedom as in the Born-Oppenheimer approximation. In this paper, we analyze the electron-photon Hamiltonian within the cavity Born-Oppenheimer approximation (CBOA), where the electronic problem is solved for fixed nuclear positions and photonic parameters. Specifically, we focus on intermolecular interactions in representative dimer complexes. The CBOA potential energy surfaces are compared with those obtained using a polaritonic approach, where the photonic and electronic degrees of freedom are treated at the same level. This allows us to assess the role of electron-photon correlation and the accuracy of CBOA.