1. a Department of Chemistry , University of Oslo , P. O. Box 1033 Blindern, N-0315 Oslo, Norway
2. b SINTEF Materials and Chemistry , P. O. Box 124 Blindern, N-0314 Oslo, Norway
3. c Department of Chemistry , Centre for Theoretical and Computational Chemistry, University of Oslo , P. O. Box 1033 Blindern, N-0315 Oslo, Norway