1. Department of Applied Mathematics, Research School of Physical Sciences and Engineering, Australian National University, Canberra, Australian Capital Territory 2601, Australia
2. Department of Chemical Physics, Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, P.R. China 230026
3. Discipline of Chemistry, University of Newcastle, Callaghan, New South Wales 2308, Australia