Strong coupling M{\o}ller-Plesset perturbation theory

TL;DR

This paper develops a strong coupling quantum electrodynamical M{ }ller-Plesset perturbation theory using a polaritonic orbital basis, improving the description of electron-photon interactions in strongly coupled light-matter systems.

Contribution

It introduces a novel polaritonic orbital basis for perturbation theory in the strong coupling regime, addressing a key theoretical challenge in the field.

Findings

The new approach provides a more accurate description of cavity-induced electron-photon correlations.

Assessment of different orbital choices highlights the importance of a consistent molecular orbital framework.

The method demonstrates strengths and limitations in modeling strongly coupled light-matter systems.

Abstract

Perturbative approaches are methods to efficiently tackle many-body problems, offering both intuitive insights and analysis of correlation effects. However, their application to systems where light and matter are strongly coupled is non-trivial. Specifically, the definition of suitable orbitals for the zeroth-order Hamiltonian represents a significant theoretical challenge. While reviewing previously investigated orbital choices, this work presents an alternative polaritonic orbital basis suitable for the strong coupling regime. We develop a quantum electrodynamical (QED) M{\o}ller-Plesset perturbation theory using orbitals obtained from the strong coupling QED Hartree-Fock. We assess the strengths and limitations of the different approaches and emphasize the essential role of using a consistent molecular orbital framework to achieve an accurate description of cavity-induced electron-photon correlation effects.