1. Kenneth S. Pitzer Center for Theoretical Chemistry, Department of Chemistry, University of California, Berkeley, California 94720, United States
2. Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
3. van ’t Hoff Institute for Molecular Science, University of Amsterdam, P.O. Box 94157, 1090 GD Amsterdam, The Netherlands
4. NASA Ames Research Center, Moffett Field, California 94035-1000, United States
5. Leiden Observatory, Leiden University, P.O. Box 9513, 2300 RA Leiden, The Netherlands
6. Astronomy Department, University of Maryland, College Park, Maryland 20742, United States