Nonzero angular momentum pairing correlation in shell model

A simple approximation to shell model is proposed in which the low energy excitation spectra corresponds to the identical nucleons occupying the same single particle states where they preferred to form pairs for the ground states. We call this approximation as nonzero angular momentum pairing shell model. It not only reduces the dimensionality of the shell model but also matches the number of low energy levels in experimental spectra for few cases where exact shell model predicts many more states. The special focus has been done to consider the realistic interaction derived from free nucleon-nucleon scattering data to cope with the experimental spectra. The proposed approximation to shell model has been applied to calculate the energy spectra of O18 and Ni58 nuclei where only two neutrons occupy the valence states outside the core. When compared with the experimental data, the results are found to be encouraging. It is expected that results will be more pronounced if the even-even nuclei with higher number of valence nucleons are considered.