This project in molecular electronic structure theory is supported by the NSF Theoretical and Computational chemistry Program. Ab initio electron propagator theory (EPT) is applied to the computation of ionization potentials, electron affinities, and related properties. Improved computer codes for EPT computations will be developed using algorithms adapted from other areas of ab initio theory. These include the computation of second and third-order quasiparticle and renormalized self-energy for large molecules using direct generation of electron-repulsion integrals, density basis sets, and elimination of energy denominators using Laplace transform techniques. These methods will be implemented in parallel code for a small cluster of workstations. The theory will be applied to multiply charged carbon cluster anions and to organometallic radicals. Like all ab initio methods for the calculation of the electronic structure of molecules, electron propagator theory (EPT) is based on the fundamental equations of quantum mechanics. The EPT equations provide a more direct route to the rigorous calculation of electron excitation energies and thus of spectroscopic excitations, ionization energies, and electron affinities. The emphasis in this project is on the development of improved computational methods and their implementation on parallel computers, particularly, on clusters of workstations.
