MICHAEL P. DOYLE, PhD, was D. R. Semmes Professor of Chemistry at Trinity University in San Antonio, Texas, and is currently Professor of Chemistry at the University of Arizona in Tucson. M. ANTHONY McKERVEY, PhD, is Professor of Chemistry and Director of QUCHEM at Queen's University in Belfast, Northern Ireland. TAO YE, PhD, is a Postdoctoral Fellow in the Department of Chemistry at the University of Nottingham in Great Britain.