1. Université Paris-Est, Laboratoire Modélisation et Simulation Multi Echelle, MSME UMR 8208, CNRS, UPEC, UPEM, 5 Bd Descartes, Champs-sur-Marne, Marne la Vallée F-77454, France
2. Department of Theoretical Physics and Astronomy, Herzen University, Moika 48, St. Petersburg 191186, Russia
3. LERMA, Observatoire de Paris, Sorbonne University, UPMC Univ. Paris 06, CNRS-UMR 8112, F-92195 Meudon France