1. Department of Mathematics, Michigan State University, East Lansing, MI 48824 USA.
2. Department of Mathematics, Department of Computational Mathematics, Science, and Engineering, Michigan State University, East Lansing, MI 48824 USA.
3. Department of Computational Mathematics, Science, and Engineering, Michigan State University, East Lansing, MI 48824 USA.
4. National Superconducting Cyclotron Laboratory and Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824 USA.
5. Department of Mathematical Sciences, Tsinghua University, Beijing 100084, China; and Yanqi Lake Beijing Institute of Mathematical Sciences and Applications, Beijing 101408, China.