1. Department of Physics and Astronomy, Rutgers University, Piscataway, New Jersey 08854-8019, USA;
2. Center for Physical Sciences and Technology, LT-10257 Vilnius, Lithuania
3. Center for Computational Materials Science, United States Naval Research Lab, Washington, DC 20375-0001, USA
4. Department of Materials Science and Engineering, University of Delaware, Newark, Delaware 19716-3106, USA
5. Materials Department, University of California, Santa Barbara, California 93106-5050, USA