1. Dipartimento di Colture Arboree, University of Bologna, viale Fanin 46, Bologna 40127, Italy
2. Departamento de Fisica, Universidade Federal do Amazonas, Manaus, Amazonas 69077-000, Brazil
3. Theoretical and Computational Physics, Simulation Laboratory of Nanostructured Systems, University Babes-Bolyai, Str. Mihail Kogalniceanu nr. 1, Cluj-Napoca 400084, Romania
4. Dipartimento di Chimica "Giacomo Ciamician", University of Bologna, via Selmi 2, Bologna 40126, Italy
5. Dipartimento di Matematica, University of Bologna, Piazza di Porta San Donato 5, Bologna 40126, Italy