1. Institute for Molecular Science, Okazaki 444, Japan, Polymer Synthesis, Yokkaichi Research Laboratory, Tosoh Corporation, 1-8, Kasumi, Yokkaichi 510, Japan, School of Informatics and Sciences, Nagoya University, Nagoya 464-01, Japan, and Cherry L. Emerson Center for Scientific Computation and Department of Chemistry, Emory University, Atlanta, Georgia 30322