1. Instituto de Física, Universidade de São Paulo, Caixa Postal 66318,
05314-970 São Paulo, SP, Brazil
2. Department of Theoretical Chemistry
and Biology, School of Biotechnology, Royal Institute of Technology, SE-106 91 Stockholm, Sweden
3. Department of Physics, Chemistry
and Pharmacy, University of Southern Denmark, Campusvej 55, DK-5230 Odense M, Denmark