1. Department of Mathematics, Wayne State University, 656 W. Kirby, Detroit, Michigan 48202, USA
2. Department of Chemistry, Wayne State University, 5101 Cass Ave., Detroit, Michigan 48202, USA
3. Theoretical Division, Center for Nonlinear Studies, and Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA