[1] Berg Univ Wuppertal, D-42119 Wuppertal, Germany
[2] Forschungszentrum Julich, Julich Supercomp Ctr, D-52425 Julich, Germany
[3] Eotvos Lorand Univ, Inst Theoret Phys, H-1117 Budapest, Hungary
[4] MIT, Ctr Theoret Phys, Cambridge, MA 02139 USA
[5] Univ Aix Marseille 2, CNRS, Ctr Phys Theor, UMR 6207,CNRS Luminy, F-13288 Marseille 9, France