| dc.description.abstract | Chemical properties and reactivity are influenced by many external factors, such as temperature, pressure, solvents, and electric fields. In spectroscopy, molecules are probed using light, which yields information about the molecular structure. Optical cavities are used to trap light together with molecules, forming a strong interaction between the two. This interaction yields hybrid light-matter states called polaritons, with different properties and energies compared to their individual components. Recent results have shown that light-matter coupling can influence chemical reactions, even in the absence of photons in the cavity due to the vacuum fluctuation of the electromagnetic field. The understanding of polariton chemistry, the study of these hybrid light-matter states at the intersection of quantum chemistry and quantum optics, is needed to understand which chemical and physical properties are influenced by this strong light-matter coupling.
Coupled cluster theory is a well-established theory within quantum chemistry and is used to obtain the electronic structure of molecules and other electronic properties such as dipole moments, polarizabilities, and excitation energies. In this thesis, I present quantum electrodynamics coupled cluster theory, an extension of coupled cluster theory to photons, to describe strong light-matter interaction and the resulting polaritons. This theory can describe both photons and the electronic structure at the same level of accuracy, which is vital to describe interactions between the two accurately. The thesis includes six papers on polaritonic chemistry. The publications include ab initio theory for ground states, excited states, intermolecular interactions, and insights into the connections between molecular and polaritonic properties. | en_US |
