1. Department of Engineering, Lancaster University, Bailrigg, Lancaster LA1 4YW, U.K.
2. Department of Chemistry, Lancaster University, Bailrigg, Lancaster LA1 4YB, U.K.
3. Scientific Computing Department, Science and Technology Facilities Council, Daresbury Laboratory, Warrington WA4 4AD, U.K.
4. Materials Science Institute, Lancaster University, Bailrigg, Lancaster LA1 4YB, U.K.