Neutron-proton quadrupole interaction in the nucleon-pair shell model - art. no. 037303

The nucleon-pair shell model truncated to the S-D subspace is applied to nu cleus Ba-134 for examining the effects on collectivity due to long-range n- p quadrupole forces. It is found that symmetric and mixed-symmetric states, consequently M1 transitions, are primarily controlled by the n-p quadrupol e interaction. In comparison with surface-delta interaction, when the quadr upole n-p Coupling is weak, the model can produce approximately the vibrati onal limit. and when the quadrupole n-p coupling is strong, the O(6) limit can be realized.