Calculation of the Raman optical activity via the sum-over-states expansion

A new ab initio calculational method for simulations of the Raman optical activity spectra is proposed. The method is based on the sum-over-states formalism (SOS). Unlike the finite difference coupled-perturbed calculations (CP) used previously, the new scheme provides analytical derivatives of the polarization tensors and is less demanding with respect to the computer power. Although the new method is not suitable for accurate benchmark calculations, similar accuracy of the SOS and CP results was observed for the spectra of α-pinene and trans-pinane.