||Chemistry, Physical, diffusion, dynamics, energy relaxation, Linearized semiclassical method, liquid bromoform, n-methylacetamide, Physics, Atomic, Molecular & Chemical, polyatomic-molecules, room-temperature, simulations, spectral, supercritical fluids, terminal acetylenes
||Studies of vibrational energy flow in various polar and nonpolar molecules that follows the ultrafast excitation of the CH and CH stretch fundamentals, modeled using semiclassical methods, are reviewed. Relaxation rates are calculated using Landau-Teller theory and a time-dependent method, both of which consider a quantum mechanical solute molecule coupled to a classical bath of solvent molecules. A wide range of decay rates are observed, ranging from 1 ps for neat methanol to 50 ps for neat bromoform. In order to understand the flow rates, it is argued that an understanding of the subtle mixing between the solute eigenstates is needed and that solute anharmonicities are critical to facilitating condensed phase vibrational relaxation. The solvent-assisted shifts of the solute vibrational energy levels are seen to play a critical role of enhancing or decreasing lifetimes.