1. Bogolyubov Institute for Theoretical Physics, 03680 Kiev, Ukraine
2. Laboratory on Quantum Theory in Linköping, Box 8017, SE-580 08 Linköping,
Sweden
3. Division of Organic
Chemistry,
Department of Physics, Chemistry, and Biology, Linköping University, SE-581 83 Linköping, Sweden
4. Division of Molecular Physics,
Department of Physics, Chemistry, and Biology, Linköping University, SE-581 83 Linköping, Sweden
5. Department of Nanoengineering, Center for Physical Sciences and Engineering, Savanoriu
231, LT-02300 Vilnius, Lithuania