1. Department of Materials Science and Engineering, International Institute of Nanotechnology, Northwestern University, Evanston, Illinois 60208, United States
2. Theoretical Science Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur PO, Bangalore 560064, India
3. Central Department of Physics, Tribhuvan University, Kathmandu, 8212 Nepal
4. Department of Electrical Engineering and Computer Science, Northwestern University, Evanston Illinois 60208, United States
5. International Centre for Materials Science and CSIR Centre of Excellence in Chemistry, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur PO, Bangalore 560064, India