n-p Interaction Effects on the Double Beta Decay Nuclear Matrix Elements for Medium Mass Nuclei

The quality of HFB wave functions are tested by comparing the theoretically calculated results with the available experimental data for a number of spectroscopic properties like yrast spectra, reduced B(E2) transition probabilities, quadrupole moments and g-factors for the nuclei involved in 2$\nu $ $\beta \beta $ decay. It is observed that the np interactions vis-\`{a}-vis the deformations of the intrinsic ground states of medium mass nuclei play a crucial role in the fine tuning of the nuclear matrix elements, M$_{2\nu}.$