  The exotic even-even isotopic chains from Z=32 to Z=38 are investigated by
means of the relativistic Hartree-Bogoliubov (RHB) approach with the explicit
Density Dependent Meson-Exchange (DD-ME2) and Density Dependent Point-Coupling
(DD-PC1) models. The classic magic number N=50 is reproduced and the new number
N=70 is predicted to be a robust shell closure by analysing several calculated
quantities such as: two-neutron separation energies, two-neutron shell gap,
neutron pairing energy, potential energy surface and neutron single particle
energies with and without the tensor force. The obtained results are
corroborated by shell model calculations and compared with the predictions of
finite range droplet model (FRDM) and with the available experimental data. A
reasonable and satisfactory agreement between the theoretical models and
experiment is established.
