1. Applied Physics Department, State University of Campinas, Campinas, SP 13083-970, Brazil
2. Center for Computational Engineering & Sciences - CCES, State University of Campinas, Campinas, SP 13083-970, Brazil
3. Alan G. MacDiarmid NanoTech Institute, University of Texas at Dallas, Richardson, Texas 75080, United States
4. Physics Department, Federal University of Paraná - UFPR, Curitiba, PR 81531-980, Brazil