1. Department of Materials, Loughborough University, Loughborough LE11 3TU, United Kingdom
2. Institut für Theoretische Physik, Universität Tübingen, Tübingen, Germany
3. Department of Mathematical Sciences, Loughborough University, Loughborough LE11 3TU, United Kingdom
4. Interdisciplinary Centre for Mathematical Modelling, Loughborough University, Loughborough LE11 3TU, United Kingdom