1. Department of Physics, Harvard University, Cambridge, MA 02138, USA
2. School of Chemistry, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
3. Harvard John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA
4. Department of Chemistry and Biochemistry, San Diego State University, San Diego, CA 92182, USA
5. Viral Information Institute, San Diego State University, San Diego, CA 92182, USA