1. Department of Mathematical Sciences, Loughborough University, Loughborough LE11 3TU, UK
2. Center for Nonlinear Science, Georgia Institute of Technology, Atlanta, Georgia 30332-0430
3. Chemical Physics Department, The Weizmann Institute of Science, 76100 Rehovot, Israel
4. Center for Computational Molecular Sciences & Technology, School of Chemistry & Biochemistry, Georgia Institute of Technology, Atlanta, Georgia 30332-0400