1. Instituto de Física, Universidade de São Paulo, Caixa Postal 66318, 05314-970 São Paulo, SP, Brazil
2. Departamento de Ciências da Natureza, Matemática
e Educação, Universidade Federal de São Carlos, Rod. Anhanguera − Km 174, 13600-970 Araras, SP, Brazil
3. Department of Theoretical Chemistry and Biology, School of Biotechnology, Royal Institute of Technology, SE-106 91 Stockholm, Sweden
4. Department of Physics, Chemistry and Pharmacy, University of Southern Denmark, Campusvej 55, DK-5230 Odense M, Denmark