Professor Kenneth D. Jordan at the Department of Chemistry, University of Pittsburgh, is supported by a grant from the Theoretical and Computational Chemistry Program at NSF for studies related to the electronic and geometric structure of molecular systems. His work under this grant is, primarily, in three areas. The first research area concerns the thermodynamic properties of modest size clusters. This work involves accurate quantum chemical determination of the total interaction energy for various cluster geometries followed by simulation of the dynamics of motion on the energy surfaces. The second area concerns the study of reactions on a Si surface. For this work, finite clusters are being used to model the motion and reaction of adsorbates on and with the surface. Finally, research is being carried out to validate and to extend various theoretical methods which are used for the study of larger molecules and clusters. Theoretical electronic structure methods have been firmly established and are regularly applied at two extremes; at one extreme are small systems composed of only a few atoms and at the other extreme are crystalline solids. The work under this grant deals with the intermediate case of clusters which are being studied for two scientific purposes. The first reason is to examine the properties of matter in the intermediate state between the extremes; this state is especially important because it has properties which are fundamentally different from those at the extremes. The work under this grant is helping to explore these fascinating and potentially useful cluster properties. The second reason is to study the properties of the surfaces of solids with suitable cluster models. Such models are especially useful to elucidate surface chemistry because they enable theory which explains and predicts chemistry in molecules to be applied to processes which occur at the surfaces of condensed matter.
