A Classical Theory for the Raman Optical Activity

A classical theory for the Raman optical activity (ROA) is proposed based on a picture that for a normal mode, atoms of a molecule with partial residual charges act as oscillating dipoles around their equilibrium positions, which also induce magnetic moments on the other atoms (dipoles), reciprocally. Then the resulting coupling between electric dipoles and magnetic moments of the molecule contributes to the optical activity. Despite its crude approximation, this model offers a physical essence for ROA and produces results that are of quality comparable to the complicated quantum-chemical calculation, as far as the sign of the circular intensity difference for the ROA is concerned.