[1] Departments of Chemistry, University of Sheffield, Sheffield S10 2TN, United Kingdom
[2] Department of Automatic Control and Systems Engineering, University of Sheffield, Sheffield S10 2TN, United Kingdom
[3] Department of Information Studies, University of Sheffield, Sheffield S10 2TN, United Kingdom
[4] GlaxoSmithKline Research and Development, Gunnels Wood Road, Stevenage SG1 2NY, United Kingdom