1. Pôle de
Chimie Théorique, UMR-CNRS PASTEUR, Ecole Normale Supérieure, 24, rue Lhomond, 75231 Paris Cedex 05, France
2. Department
of Chemistry, Rice University, P.O. Box 1892, MS-60, Houston, Texas 77251-1892, United States
3. Department
of Physical Chemistry, ELTE Eötvös Loránd University, Budapest 112,
P.O. Box 32, H-1518 Budapest, Hungary