Strong light-matter coupling in an optical cavity could be used as a tool to tweak intermolecular forces, and subsequently the properties of large molecular systems.
Haugland et al. investigated how strong light-matter coupling inside an optical cavity modifies intermolecular forces. The authors modeled correlated electron-photon systems from first principles with two methodologies, quantum electrodynamical density functional theory (QEDFT) and quantum electrodynamics coupled cluster theory (QED-CC).
They looked at four types of interactions: van der Waals interaction, dipole-induced dipole interaction, hydrogen bonding, and cavity mediated long-range interactions. They found the optical cavity affected these interactions in chemically counterintuitive ways.
The van der Waals interaction behaved differently inside the cavity, and in a way that cannot be adequately explained with electrostatics. Instead, it behaved like a quantum phenomenon caused by strong light-matter interaction. The authors also observed the cavity to affect the dipole-induced dipole and hydrogen bonding interactions, reducing their binding energies and polarizabilities more than it does to the van der Waals interaction.
These results support the notion that a quantum electromagnetic field inside an optical cavity could be used as a tool to alter intermolecular forces, with potential applications in solvation processes, the formation of biological macromolecules and other fields. Tuning the field polarization and frequency of the cavity could change the stability, electron densities, dipole moments, and polarizabilities of intermolecular interactions.
“This work is the first to show that intermolecular interactions can be modulated by a quantum field, and this might have implications for several areas of chemistry,” said author Henrik Koch. “We are tempted to predict that, within the next decade, the quantum vacuum will captivate researchers in several areas of chemistry.”
Source: “Intermolecular interactions in optical cavities: An ab initio QED study,” by Tor S. Haugland, Christian Schäfer, Enrico Ronca, Angel Rubio, and Henrik Koch, Journal of Chemical Physics (2021). The article can be accessed at https://doi.org/10.1063/5.0039256.
This paper is part of the Polariton Chemistry: Molecules in Cavities and Plasmonic Media special topic, learn more here.
