1. Department of Applied Mathematics, University of California 1 , Merced, California 95343, USA
2. Department of Chemistry, Korea Advanced Institute of Science and Technology 2 , Daejeon 34141, South Korea
3. Department of Physics and Astronomy, San Jose State University 3 , San Jose, California 95192, USA
4. Center for Computational Sciences and Engineering, Lawrence Berkeley National Laboratory 4 , Berkeley, California 94720, USA