1. Department of Mathematics and Physics “E. De Giorgi”, University of Salento, Campus Ecotekne, via Arnesano, 73100 Lecce, Italy
2. CNR NANOTEC─Istituto di Nanotecnologia, c/o Campus Ecotekne, Via Monteroni, 73100 Lecce, Italy
3. CNR─Istituto di Cristallografia, via Amendola, 122/o, 70126 Bari, Italy
4. Materials Simulation and Modelling, Department of Applied Physics, Eindhoven University of Technology, 5600 MB Eindhoven, The Netherlands
5. Center for Computational Energy Research, Department of Applied Physics, Eindhoven University of Technology, 5600 MB Eindhoven, The Netherlands
6. National Research Council, Institute for Chemical and Physical Processes (CNR-IPCF), Via G. Moruzzi 1, Pisa 56124, Italy
7. Department of Chemistry and Industrial Chemistry, University of Pisa, Via G. Moruzzi 13, Pisa 56124, Italy
8. CNR NANOTEC─Istituto di Nanotecnologia─c/o Dipartimento di Chimica, Università di Bari, Via Orabona 4, 70125 Bari, Italy