Date of Award
Doctor of Philosophy
Andrew E. DePristo
Two distinct areas within theoretical chemical physics are investigated in this dissertation. First, the dynamics of collinear exchange reactions is treated within a semiclassical Gaussian wavepacket (GWP) description. Second, a corrected effective medium (CEM) theory is derived which yields: (1) a one-active-body description of the binding energy between an atom and an inhomogeneous host; and (2) an N-active-body description of the interaction energy for an N atom system;To properly treat the dynamics of collinear exchange reactions, two extensions to the previous methodology of GWP dynamics are presented: (1) evaluation of the interaction picture wavefunction propagators directly via the GWP solution to the time-dependent Schrodinger equation; and (2) use of an expansion of GWPs to represent the initial translational plane wave. This extended GWP dynamical approach is applied to the H + H[subscript]2 collinear exchange reaction using the Porter-Karplus II potential energy surface;A one-active-body CEM theory is derived (denoted CEM-1) which describes binding between a single atom and an inhomogeneous host. The zeroth order term of the interaction energy is provided by a self-consistent calculation of the embedding energy of the atom into spin-unpolarized jellium. Higher order terms provide corrections of two sorts: (1) the Coulomb interaction between the charge densities on the atom and the host; and (2) the difference in kinetic-exchange-correlation energies between the atom/inhomogeneous host system and the atom/jellium system. The CEM-1 method is used to evaluate the interaction energies for: (1) H atom embedded into spin-polarized jellium; (2) some H atom containing diatomic molecules; and (3) H atom chemisorption on Ni(100), Cu(100), and Fe(110);The CEM-1 theory is then extended to provide an N-active-body theory (denoted CEM-N) where each atom in the N atom system is allowed to interact with the remaining (N - 1) atoms in a simultaneous fashion. The CEM-N method is tested by considering a variety of homonuclear diatomic molecules. These results illustrate the need for a new set of "covalent" embedding energies which are provided.
Digital Repository @ Iowa State University, http://lib.dr.iastate.edu/
Joel David Kress
Kress, Joel David, "Topics in chemical physics: I. Semiclassical reactive scattering theory; II. Corrected effective medium theory " (1987). Retrospective Theses and Dissertations. 8668.