1. Nuclear Engineering and Nonproliferation Division, Los Alamos National Laboratory, Los Alamos, NM 87545, USA
2. Computational Physics Division, Los Alamos National Laboratory, Los Alamos, NM 87545, USA
3. Department of Materials Science and Applied Mathematics, Malmö University, SE-205 06 Malmö, Sweden
4. Division of Mechanics, Materials and Component Design, Lund University, P.O. Box 118, SE-221 00 Lund, Sweden