1. Department of Physics, University of Bath, Bath BA2 7AY, United Kingdom
2. Mathematical Sciences, University of Southampton, Southampton SO17 1BJ, United Kingdom
3. CSIRO Energy, Newcastle Energy Centre, 10 Murray Dwyer Circuit, Mayfield West, NSW 2304, Australia
4. Department of Chemistry, University of Bath, Bath BA2 7AY, United Kingdom
5. Department of Mathematics, University of Portsmouth, Portsmouth PO1 3HF, United Kingdom