The Theoretical and Computational Chemistry program is supporting Prof. B.Whaley at the University of California, Berkeley. The research, to be carried out over the next three years will be a a continuation of ongoing theoretical studies of foreign species in quantum clusters of helium and hydrogen. This research program has a two-fold design. First, to establish general methods of dealing with structure, dynamics and spectroscopy of complex quantum systems when nuclear delocalization and exchange effects are important. The approach is based on Quantum Monte Carlo methods, both zero and finite temperature, which have been shown to be powerful tools for analyzing the properties of quantum clusters. A significant algorithmic development here is the calculation of imaginary time correlation functions, which allows the calculation of dopant spectra directly. The second goal is to answer some open questions about the interaction of probe molecules with their quantum environment which have been raised by recent experiments on doped quantum clusters. Thus in the applications during this grant cycle, Prof Whaley will focus on the study of the spectroscopy of these clusters. This includes infra-red spectra of dopant molecules, electronic spectra and the nature of electronic energy transfer in pure and atomic-doped quantumclusters. Quantum clusters of helium and hydrogen possess unusual low temperature behavior which is of interest to both chemistry and physics communities. While conceptually of importance because of the unique opportunity they present for study of finite size effects in strongly quantum systems, theyalso have significant practical use as gentle quantum matrices which may be utilized to study spectroscopy of weakly bound systems and chemical reactions at low temperatures. The utility of this quantum micro-environment has recently been dramatically demonstrated with the production of small metal clusters inside a helium droplet. This opens a new controlled route to study of the reactivity of metal particles. The aim of this theoretical and computational investigation is to develop the understanding necessary to interpret spectral signatures of such doped quantum clusters, and to provide predictive power for using them to control elementary reaction dynamics in a novel ultra-cold nanoscale quantum matrix.
