Recent rapid progress in quantum chemical calculations has made it possible to perform the first principle calculations of various molecular spectroscopies and photophysical processes. Anharmonic effect on molecular electronic absorption and luminescence like fluorescence and phosphorescence spectroscopies and electronic relaxation processes like internal conversion and intersystem crossing has been theoretically developed 10 years ago. This chapter reviews its applications to pyridine, pyrimdine, pyrazine, and fluorobenzene. It then presents the molecular theories of all types of sum-frequency generation (SFG) including both vibrational SFG (VSFG) and electronic SFG (ESFG). A couple of SFG examples based on the quantum chemical calculations are included for demonstration. The chapter presents how to perform the calculations of the intramolecular vibrational redistribution (IVR) for water clusters and amino acid molecules and their peptides. It applies the femto-second (fs) time-resolved density matrix method to treat the Bixon-Jortner (B-J) model which is a popular method for studying photophysical process.
- Femto-second (fs) time-resolved density matrix method
- Intramolecular vibrational redistribution (IVR)
- Molecular spectroscopies
- Quantum chemical calculations
- Sum-frequency generation (SFG)