1. Current address: Department of Chemistry, Wayne State university, Detroit, Michigan 48202.
2. H.B. Schlegel, J. Comput. Phys., to be published;
3. Ph.D. thesis, Queen's University, Kingston, Ont. Canada, 1975.
4. H.B. Schlegel and J.S. Binkley, J. Comput. Phys., to be published.
5. J.A. Pople, R. Krishnan, H.B. Schlegel and J.S. Binkley, Int. J. Quantum Chem.: Quantum Chem. Sym. 13, 225 (1979).