1. Institute of Solid State Physics, University of Latvia, Kengaraga 8, LV-1063 Riga, Latvia
2. Institute of General and Inorganic Chemistry, Russian Academy of Science, Leninskii prosp. 31, 119991 Moscow, Russia
3. Institute of Chemistry, Saint Petersburg State University, Universitetskaya nab. 7/9, 199034 Saint Petersburg, Russia
4. Theoretical Chemistry Department, University of Duisburg-Essen, Universitätstr. 2, 45141 Essen, Germany