1. a Institut für Physikalische Chemie , Universität Mainz , Mainz , D-55099 , Germany
2. b Centre for Theoretical and Computational Chemistry, Department of Chemistry , University of Oslo , Oslo , N-0315 , Norway
3. c Institute for Theoretical Chemistry, Department of Chemistry and Biochemistry , The University of Texas at Austin , Austin , TX , 78712 , USA
4. d Institut für Nanotechnologie, Karlsruher Institut für Technologie (KIT) , Karlsruhe , D-76021 , Germany
5. e Dipartimento di Chimica ‘Giacomo Ciamician’ , Università di Bologna , Via Selmi 2, Bologna , I-40126 , Italy