[1] Univ Kentucky, Ctr Computat Sci, Lexington, KY 40506 USA
[2] Fdn Res & Technol Hellas, Inst Elect Struct & Laser, Iraklion 71110, Crete, Greece
[3] Daimler AG GR PSS, D-89081 Ulm, Germany
[4] Univ S Florida, Dept Phys, Tampa, FL 33620 USA
[5] Univ Kentucky, Dept Phys, Lexington, KY 40506 USA