Realization of negative mass regime and bound state of solitons in inhomogeneous Bose-Einstein condensates Priyam Das, Ayan Khan and Prasanta K. Panigrahi Eur. Phys. J. D, 70 5 (2016) 113 Published online: 19 May 2016 DOI: 10.1140/epjd/e2016-70113-x