Semiclassical Model for Vibrational Dynamics in Polyatomic Molecules: Investigation of Internal Vibrational Relaxation

We propose a semiclassical model describing vibrational relaxation and intramolecular vibrational energy redistribution (IVR) in polyatomic molecules. Transition rates between different harmonic states are found using the generalized self-consistent Marcus-Levich-Jortner approach, treating low-frequency modes as reaction coordinates. We applied our method to the 1,4-acetylbenzonitrile molecule (AcPhCN) in order to study internal vibrational dynamics. Our analysis of internal vibrational dynamics following photoexcitations of CN and CO stretch modes is consistent with recent experimental data.