1. Contribution from the State Key Laboratory of Physical Chemistry of Solid Surfaces, Center for Theoretical Chemistry, and Department of Chemistry, Xiamen University, Xiamen 361005, P. R. China, Laboratoire de Chimie Physique, Groupe de Chimie Théorique, Université de Paris-Sud, 91405 Orsay Cédex, France, and Department of Organic Chemistry and the Lise Meitner-Minerva Center for Computational Quantum Chemistry, The Hebrew University, Jerusalem 91904, Israel