1. a Department of Chemistry , Johns Hopkins University , Baltimore , MD 21218 , USA
2. b Department of Chemistry , University of Gdańsk , Sobieskiego 18 , 80-952 Gdańsk , Poland
3. c Computational Research Division, Lawrence Berkeley National Laboratory , Berkeley , CA 94720 , USA
4. d Chemistry-School of Engineering and Physical Sciencs, Heriot-Watt University , Edinburgh EH14 4AS , UK