1. Pritzker School of Molecular Engineering, University of Chicago, Chicago, IL 60637, USA
2. OpenEye Scientific, Cadence Molecular Sciences, Boston, Massachusetts 02114, USA
3. Department of Physics, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong
4. Departamento de Física, Universidad Autónoma Metropolitana Iztapalapa, Av. San Rafael Atlixco 186, Ciudad de México 09340, Mexico
5. Materials Science Division, Argonne National Laboratory, Lemont, IL 60439, USA