1. Department of Chemistry, University of California, Berkeley, California 94720, Laboratory of Molecular Structure and Quantum Mechanics, Department of Chemistry, Moscow State University, Moscow 119991, Russia, Department of Chemistry, Oakland University, Rochester, Michigan 48309, Faculty of Chemistry, University of Warsaw, Pasteura 1, 02-093 Warszawa, Poland, and Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720