8351
J. Phys. Chem. 1992,96, 8351-8356 (23) (a) Krishnan, R.; Binkley, J. S.; Secger, R.; Pople, J..A. J . Chem. Phys. 1980, 72, 650. (b) Standard polarization functions were used: H ( j ~ = 0.75), C ( d = 0.626), N ( d = 0.913). 0 ( d = 1.292). (24) Hehre, W. J.; Radom, L.; v. R. Schleyer, P.; Pople, J. A. Ab Initio Molecular Orbital Theory; John Wiley & Sons, Inc.: New York, 1986; p 321. (25) Foster, J. M.; Boys, S. F. Reu. Mod. Phys. 1960, 32, 300. (26) Bader, R. F. W.; Nguyen-Dang, T. T.;Tal, Y. Rep. Prog. Phys. 1981, 44, 5679. (27) Davidson, N. Sratisrical Mechanics; McGraw-Hill: New York, 1962. (28) Pauline, L. C. The Nature Of The Chemical Bond And The Structure Of Molecules And Crystals: An Introduction To Modern Structural Chemistry; Cornell University Press: Ithaca, NY, 1960. (29) The glycine zwitterion shown here was optimized at the RHF/631G(d) level of theory within the C, point group. The in-plane amine hy-
H
