1. Independent Researcher, Toronto, Canada
2. Department of Chemistry and Cherry L. Emerson Center for Scientific Computation, Emory University, Atlanta, GA, USA
3. Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York, NY, USA
4. Department of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA, USA
5. Dipartimento di Chimica, Università degli Studi di Milano, Milano, Italy