Polarizable Embedding Based on Multiconfigurational Methods: Current Developments and the Road Ahead

This perspective gives a brief overview of recent developments within the polarizable embedding (PE) method - a multiscale approach developed over the last years. In particular, we are concerned with a recent coupling of the PE method to a multiconfiguration self-consistent field (MCSCF) code. Current applications and target systems are outlined, and methods to incorporate dynamical correlation are discussed. With respect to dynamical correlation, the focus is on perturbative treatments as well as a range-separated multiconfigurational hybrid between MCSCF and density functional theory (MC-srDFT). A short discussion of CAS active spaces is also given. A few sample results using a retinal chromophore surrounded by a protein environment illustrate both the importance of the choice of active space and the importance of dynamical correlation.