1. Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
2. Department of Mechanical and Aerospace Engineering, University of California, Davis, Davis, California 95616, USA
3. Institute for Computational Molecular Science, Temple University, Philadelphia, Pennsylvania 19122, USA
4. Department of Mathematics, Temple University, Philadelphia, Pennsylvania 19122, USA
5. Department of Mathematics, University of California, Davis, Davis, California 95616, USA