1. Institute
of Physical Chemistry and Center for Computational
Sciences, Johannes Gutenberg University Mainz, Staudinger Weg
7, D-55128 Mainz, Germany
2. Physics
Department, Sapienza - Università di Roma, P.le A. Moro
5, 00185 Rome, Italy
3. Department
of Physical and Chemical Sciences, University of L’Aquila, Via
Vetoio, 67100 L’Aquila, Italy