Structure and stability of Na+Xen clusters M. Slama, K. Issa, F. E. Ben Mohamed, M. Ben El Hadj Rhouma and F. Spiegelman Eur. Phys. J. D, 70 11 (2016) 242 Published online: 17 November 2016 DOI: 10.1140/epjd/e2016-70147-0