Calculation of Vibrational Resonance R aman Spectra of Molecules Using Quantum Chemistry Methods

Abstract

The understanding and interpretation of experimental resonance Raman (RR) spectra can strongly benefit from theoretical simulations. These can be achieved by combining quantum chemistry (QC) methods to calculate the electronic and vibrational molecular properties, together with appropriate models and approximations to compute the Raman intensities. This chapter presents the main and most commonly employed approaches to calculate RR spectra using QC methods. It summarizes the theory of Raman scattering and provides several approximations in order to obtain practical expressions from which the Raman intensities can be calculated using QC methods. The properties of the excited states, i.e. energies, geometries, vibrational frequencies, transition dipole moments, and gradients can be calculated with QC methods. The chapter also describes different applications on molecular systems in order to assess the accuracy of the methods and to present the impact of different vibronic effects on the RR intensities.