Photon Many-body Dispersion: an Exchange-correlation Functional for Strongly Coupled Light-matter Systems

TL;DR

This paper introduces a new exchange-correlation functional for QEDFT, called photon MBD, which effectively models strong light-matter interactions and cavity effects in complex systems with computational efficiency.

Contribution

The paper presents photon MBD, a novel functional extending many-body dispersion to include photonic degrees of freedom for accurate strong coupling modeling.

Findings

Accurately captures anisotropic electron-photon interactions

Models beyond single-photon effects in cavity systems

Enables efficient simulations of large coupled systems

Abstract

We introduce an electron-photon exchange-correlation functional for quantum electrodynamical density-functional theory (QEDFT). The approach, photon MBD (pMBD), is inspired by the many-body dispersion (MBD) method for weak intermolecular interactions, which is generalized to include both electronic and photonic (electromagnetic) degrees of freedom on the same footing. We demonstrate that pMBD accurately captures effects that arise in the context of strong light-matter interactions, such as anisotropic electron-photon interactions, beyond single-photon effects, and cavity modulated van der Waals interactions. Moreover, we show that pMBD is computationally efficient and allows simulations of large complex systems coupled to optical cavities.