Coupled-cluster calculations of Raman intensities and their application to N4 and N5−

Raman intensities are evaluated by numerically differentiating the analytically calculated coupled-cluster singles and doubles (CCSD) polarizabilities with respect to small geometric perturbations. The CCSD Raman intensities are calibrated by comparison to several molecules with experimentally known Raman Intensities. The CCSD Raman intensities agree well with experiment. Predictions for tetrahedral N4, and the pentazole anion N5− are reported.