6+ isomers in neutron-rich Sn isotopes beyond N=82 and effective interactions

Recent observation of the 6(+) seniority isomers and measurements of the B(E2) values in the Sn134-138 isotopes lying close to the neutron drip line have raised some questions about the validity of the currently used effective interactions in the neutron-rich region. Simpson et al. [Phys. Rev. Lett. 113, 132502 (2014)] had to modify the diagonal and nondiagonal nu f(7/2)(2) two-body matrix elements of the V lk interaction by similar to 150 keV in their shell model calculations in order to explain the data of Sn-136. In contrast, we are able to explain the observed energy levels and the B(E2) values after marginal reduction of the same set of matrix elements by 25 keV in the RCDB (renormalized CD-Bonn) interaction. The observed mismatch in reproducing the data of Sn-136 is due to the seniority mixing. Further, we do not find it necessary to consider the core excitations, and the RCDB interaction seems better suited to explain the data beyond N = 82 magic number.