1. Instituto de Matemática e Estatística, Departamento de Ciência da Computação, Universidade de São Paulo, Rua do Matão 1010, São Paulo 05508-090, SP, Brazil
2. Condensed Matter Theory Group, Materials Theory Division, Department of Physics and Astronomy, Uppsala University, P.O. Box 516, SE-751 20 Uppsala, Sweden
3. Children’s Cancer Institute, Porto Alegre 90620-110, RS, Brazil
4. Department of Physics, Indian Institute of Technology Ropar, Rupnagar 140001, Punjab, India