1. Departamento de Fisica, Universidad Autonoma Metropolitana-Iztapalapa, 09340 Mexico City, Mexico
2. Mathematical and Statistical Computing Laboratory, Division of Computational BioScience, Center for Information Technology, National Institutes of Health, Bethesda, Maryland 20819, USA
3. Joint Institute for High Temperatures, Russian Academy of Sciences, Izhorskaya 13, Bldg. 2, Moscow 125412, Russia