[1] Ludwig Maximilians Univ Munchen, Math Inst, Theresienstr 39, D-80333 Munich, Germany
[2] Munich Ctr Quantum Sci & Technol, Schellingstr 4, D-80799 Munich, Germany
[3] CALTECH, Math 253-37, Pasadena, CA 91125 USA
[4] Univ Vienna, Dept Theoret Chem, Waehringerstr 17, A-1090 Vienna, Austria
[5] Imperial Coll London, 180 Queens Gate, London SW7 2AZ, England
[6] Sirius Univ Sci & Technol, Sirius Math Ctr, 1 Olymp Ave, Soci 354340, Russia
[7] Univ Copenhagen, Dept Math Sci, Univ Pk 5, DK-2100 Copenhagen, Denmark