Different perspectives on the exact factorization for photon–electron–nuclear systems

We employ the exact factorization of a multi-component wavefunction to analyze the dynamics of interacting photons, electrons and nuclei in physical situations emerging in the regime of strong coupling between light excitations and molecular - electronic - excitations, giving rise to the so-called molecular polaritons. Nonadiabatic molecular dynamics techniques, routinely used in the field of chemical physics, have been extended to simulate photophysical and photochemical phenomena of molecular polaritons. In this work, we analyze the foundations of these techniques in the context of the exact factorization and we assess their performance on illustrative model studies.