Polarizable Embedding Approach for the Analytical Calculation of Raman and Raman Optical Activity Spectra of Solvated Systems.

We present an analytical formulation and implementation of Raman and Raman Optical Activity (ROA) spectra within a three-layer fully polarizable Quantum Mechanical (QM)/ Molecular Mechanics (MM)/Polarizable Continuum Model (PCM) approach. Polarization effects in the MM layer are modeled by exploiting the Fluctuating Charges (FQ) method, in which MM solvent atoms are endowed with electric charges that can be mutually polarized by the solute QM density. Because of its fully polarizable atomistic description, QM/FQ/PCM is able to account for specific solvent effects like those due to hydrogen bonds, providing a physical picture for protic solvents such as water. Applications to aqueous (R)-methyloxirane and (S)-methyllactate are presented, and results are compared with available experimental data.