1. Department of Mechanical Engineering, Clemson University, Clemson, South Carolina 29634-0921, United States
2. Center for Nanophase Materials Sciences and Computer Science and Mathematics Division, Oak Ridge National Laboratory, Bethel Valley Road, Oak Ridge, Tennessee 37831-6367, United States
3. Department of Physics, Applied Physics, and Astronomy, Rensselaer Polytechnic Institute, Troy, New York 12180-3590, United States