Simulations of Raman Spectra Using the Fragment Molecular Orbital Method.

We developed an approach to calculate normal Raman activities based on the fragment molecular orbital method. For this purpose, we derived the FMO gradient and coupled-perturbed Hartree-Fock equations in the presence of the static electric field. The accuracy is evaluated in comparison with full ab initio calculations for a set of closed-shell and radical systems. We applied the method to calculate Raman and IR spectra of a polystyrene oligomer and crambin (PDB: 1CRN ) and performed an assignment of peaks based on localized normal modes. The computational timings demonstrate the efficiency of the method.