1. Department of Biotechnologies, Chemistry and Pharmacy, University of Siena, 53100 Siena, Italy
2. Chemistry Department, Bowling Green State University, Bowling Green, 43403 Ohio, United States
3. Department of Chemistry, Chemical Theory Center, and Minnesota Supercomputing Institute, University of Minnesota, Minneapolis, Minnesota 55455-0431, United States
4. USIAS Institut d’Études Avanceés, Université de Strasbourg, 67083 Strasbourg, France