1. Department of Physics and Astronomy, The University of Texas at San Antonio, San Antonio, Texas 78249-5003, USA
2. Computational Research Division, Lawrence Berkeley National Lab, Berkeley, California 94700, USA
3. Institute of Molecular Biophysics, Florida State University, Tallahassee, Florida 32306, USA
4. Instituto de Física, Universidad Autónoma de San Luis Potosí, Álvaro Obregón 64, 78000 San Luis Potosí, San Luis Potosí, Mexico
5. Department of Chemistry and Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, USA