My training is in electronic structure theory and I have extensive experience in both the development of theoretical methods, and the application of these to fundamental problems of interest to various parts of NASA. Currently, most of my work is in the application of electronic structure methods to three areas: 1) the calculation of highly accurate rovibrational spectra of small molecules of interest to astronomy and astrophysics, such as the ammonia, CCH-, NH2-, and HO2+ molecules; 2) the calculation of the vertical electronic absorption or emission process in polycyclic aromatic hydrocarbons (PAHs), neutrals, cations, anions, and other derivatives, such as nitrogen substituted PAHs (PANHs), or PAH clusters; and 3) the investigation of the properties of molecules of interest in atmospheres (including Earth) such as chemical stability, thermal stability, spectroscopy (both rovibrational and electronic), Ozone Depletion Potentials (ODPs), Global Warming Potentials (GWPs), etc.

Past applications work has included investigating the properties of high-energy density materials that could be used as novel rocket fuels, such as Td N4, examining chemical reaction pathways, such as the destruction of chlorine nitrate on the surface of polar stratospheric clouds, the reaction of F + H2, or novel organic reactions (e.g., the Bergman reaction), many investigations of the rovibrational or electronic spectroscopy of novel molecules or ions, mostly in the gas-phase but also including magnesium, sulfate salts of interest to Europa, and many investigations generally determining the properties of gas-phase molecules and ions of interest in atmospheres, the interstellar medium, or other exotic environments.

Work on theoretical methods has included the development and efficient implementation (on both vector and massively parallel supercomputers) of sophisticated ab initio electron correlation methods with particular emphasis on perturbation and coupled-cluster theories. An elegant piece of work involved the formulation and implementation of efficient open-shell perturbation and coupled-cluster theories based on the use of ``symmetric spin-orbitals.'' I have extensive experience with development of analytical derivative methods applied to electron correlation approaches, and also with development of reliable diagnostics that can be used to asses the expected accuracy from a given calculation/method, such as the T1 diagnostic used in coupled-cluster theory. More recent efforts have been aimed at developing novel and accurate methods for the study of excited electronic states, and at developing a scalable coupled-cluster method by approximating certain integrals in order to reduce the amount of data necessary to perform the coupled-cluster calculation.