[1] Delft Univ Technol, Kavli Inst Nanosci, NL-2628 CJ Delft, Netherlands
[2] Univ Barcelona, Dept Quim Fis, E-08028 Barcelona, Spain
[3] Univ Barcelona, Ctr Especial Recerca Quim Teor, E-08028 Barcelona, Spain
[4] Parc Cient Barcelona, Barcelona 08028, Spain
[5] CSIC, Inst Ciencia Mat Barcelona, Cerdanyola Del Valles 08193, Spain