Theoretical Descriptions of Vibrational Energy Transfer in Gas and Liquid Phases

University Of Wisconsin-Madison, Madison WI

Investigators

Abstract

Ned Sibert of the University of Wisconsin, Madison, is supported by the Theoretical and Computational Chemistry Program to investigate theoretically energy flow in polyatomic molecules in both gas and liquid phases, using combined classical and quantum techniques. The primary goal of this effort is to develop molecular models of the dynamics that are consistent with experimental observations. This work will highlight and elucidate the mechanisms by which a system returns to equilibrium, and permit the sorting out of quantum from classical effects in relaxation processes. Research topics include the calculation of rotation-vibration spectra of methane and its deuterated analogs using perturbative techniques developed by the PI, the detailed study of gas phase relaxation of carbon disulfide and ultimately more complex systems via collisions, and the theoretical study of energy flow in the condensed phase. A quantitative analysis of the dynamics in these problems involves the accurate treatment of both the molecular eigenstates and their interactions with the surrounding environment. The research outcomes are expected to lead to an improved understanding of the competing pathways of energy flow in medium-size molecules and of the coupling terms that are responsible for these pathways. Successful modeling of atmospheric phenomena, combustion chemistry, and drug design via molecular simulations require accurate knowledge of the forces between the atoms and molecules. Recent experimental advances in ultrafast laser spectroscopy have enabled scientists to probe the time evolution of vibrationally excited systems to determine the pathways of energy flow in molecules. Outcomes from theoretical and experimental studies of vibrational energy transfer reveal potentially important information about the forces that control the above technologically important processes.