1. Laboratório de Óptica Quântica da UFSC, 88040–900 Florianópolis, SC, Brazil
2. School of Mathematics and Statistics, The University of Birmingham, Birmingham, B15 2TT, UK
3. Laboratory for Plasma Research, University of Maryland, College Park, MD 20742-3511, USA
4. HLRZ Supercomputing Center, KFA, D-5170 Jülich, Germany