FRANK WEINHOLD, PhD, is Emeritus Professor of Physicaland Theoretical Chemistry at the University ofWisconsin Madison. Professor Weinhold has served on theeditorial advisory boards of the International Journal of QuantumChemistry and Russian Journal of Physical Chemistry. He is theauthor of more than 170 technical publications and softwarepackages, including the natural bond orbital program. CLARK R. LANDIS, PhD, is Professor of Inorganic Chemistryat the University of Wisconsin Madison. He has receivedteaching and lectureship awards for his contributions to chemicaleducation. Dr. Landis's research focuses on catalysis in transitionmetal complexes.