This project in the Theoretical and Computational Chemistry Program involves the development and application of new methods for determination of electron binding energies. A computer program will be devised to implement new methods for theoretical calculations that will be more accurate than have hitherto been possible for all but very small molecules. Applications will be made to systems of current chemical interest, including transition metal carbonyls, anion-neutral complexes and organometallic compounds. The method is based on electron propogator theory, which focuses directly on the binding energy. Current methods will be augmented by inclusion of nondiagonal third order self energies, fourth order quasiparticle calculations and third order one-electron reduced density matrices. Gradients of the binding energies will also be obtained to facilitate geometry optimizations.