On the description of the environment polarization response to electronic transitions

This paper addresses the issue of accurately describing the structures and properties of electronically excited systems embedded in an environment, through multiscale approaches combining quantum-mechanical (QM) and polarizable classical representations of the system and environment, respectively. Such approaches represent an efficient strategy and allow to effectively study the excited states of molecular systems in the condensed phase, still maintaining the computational efficiency and the physical reliability of the ground-state calculations. The most important theoretical and computational aspects of the coupling between the QM system and the polarizable environment are presented and discussed. Even if these approaches already reached an evident degree of maturity, they can still be subject to further development, in order to achieve their full potential. This perspective presents an overview of the state of the art of these strategies, showing the fields of applicability and indicating the current limitations, which need to be overcome in future developments.