1. Department of Chemistry, University of Pune, Pune-411 007 India, Department of Physics, University of Pune, Pune-411 007 India, The Abdus Salam International Center for Theoretical Physics, Strada Costiera 11, I-34014, Trieste, Italy, and The Department of Chemistry, East Carolina University, Science and Technology Building, Suite 300, Greenville, North Carolina 27858-4353