1. Department of Chemical, Biological & Macromolecular Sciences; S. N. Bose National Centre for Basic Sciences; Block JD Sector III Salt Lake Kolkata 700 098 India
2. Division of Structural Biology and Bioinformatics; Indian Institute of Chemical Biology; 4, Raja S.C. Mullick Road Kolkata 700 032 India
3. Institute for Condensed Matter Physics and Laboratory for Emerging Nanometrology; TU Braunschweig; Mendelssohnstrasse 3 38106 Braunschweig Germany