Polaritonic Coupled Cluster Theory for Unpolarized Cavities Exploiting Point Group Symmetry

TL;DR

This paper extends quantum electrodynamic coupled cluster theory to unpolarized cavities by explicitly including two perpendicular cavity modes, enabling symmetry-preserving calculations of complex light-matter interactions in molecules.

Contribution

It introduces a novel QED-CC ansatz for unpolarized cavities that maintains symmetry and allows detailed excited-state analysis of molecules in such environments.

Findings

Unpolarized cavities exhibit complex excited-state landscapes with many avoided crossings.

The new method accurately describes molecules in unpolarized cavities, as demonstrated on benzene, fluorobenzene, and azulene.

Comparison shows significant differences between single polarization and unpolarized cavity models.

Abstract

We introduce a generalization of the quantum electrodynamic coupled cluster (QED-CC)wave function ansatz, to describe the strongly coupled light-matter system in an unpolarized optical Fabry-P\'erot cavity. This is achieved by explicitly treating two cavity modes in our calculation with perpendicular polarizations and demonstrate that this ansatz preserves the symmetry of an unpolarized cavity. Furthermore, exploiting point-group symmetry enables the assignment of polaritonic excited states as well as their targeted calculation. Using our implementation, the aromatic species benzene, fluorobenzene and azulene are investigated. We demonstrate that molecules in unpolarized cavities have a complicated excited-state landscapes with a plethora of avoided-crossings. We compare the results for a cavity with a single polarization to those of an unpolarized cavity described by two perpendicular polarization vectors using the excited states of the H$_2$ molecule as an example.