Chapter 39 - SAC-CI method applied to molecular spectroscopy

Abstract

This chapter describes the SAC–CI (Symmetry-Adapted Cluster– Configuration Interaction) method applied to molecular spectroscopy. The SAC–CI method was proposed in 1978 as an accurate electronic-structure theory for the ground, excited, ionized, electron-attached, and high-spin states of atoms and molecules. Since then, it has been successfully applied to various chemistries including more than 150 molecules and established to be a useful method for studying chemistry and physics involving various electronic states. The topics covered in the chapter are electronic excitation spectra, ionization spectra, collision-induced absorption processes, photochemical reactions, inner-shell ionizations, equilibrium geometries of excited states, and ESR hyperfine splitting constants of radicals. The applied systems are organic and inorganic compounds, vander Waals complexes, transition metal complexes, phthalocyanines, and the bacterial photosynthetic reaction center. These results show the reliability and applicability of the SAC–CI method for studying molecular spectroscopy.