Investigating Intermolecular Interactions in Optical Cavities: Benzene Stacking in the Strong Light-Matter Coupling Regime

Recent advances in optical confinement have granted a more active role to light in the task of controlling chemical properties. In the so-called strong-coupling regime, hybrid electron-photon states, or polaritons, emerge and are crucial to understanding changes in material properties inside cavities. It has also been recently proposed that strong-light matter coupling can lead to cavity modulated van der Waals interactions, altering the behavior of long-range dispersion interactions. Our group has recently proposed a framework, named photon many-body dispersion (pMBD), to model such effects within the framework of QEDFT.

In this work, we explore the impact of strong light-matter coupling on intermolecular interactions, focusing on benzene stacking in cavities. We study how cavity-induced effects modify the potential energy surface of benzene dimers under cavity regimes. Using the pMBD method, we find that, if the cavity is polarized along the x and y axes, we observe an enhancement of the attractive vdW interactions, while a z-polarized polarized cavity induces more repulsive interactions. We attempt to investigate what leads to such behavior by computing electronic and photonic observables, such as the number of photons in the ground state of the polaritonic wave function.