1. Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400 076, India
2. Theoretical Chemistry Section, Bhabha Atomic Research Centre, Mumbai 400 094, India
3. Indian Institute of Science Education and Research Kolkata, Mohanpur, Nadia 741 246, West Bengal, India
4. Physical and Materials Chemistry Division, CSIR-National Chemical Laboratory, Pune 411 008, India