An exact solution of nuclear spherical mean-field plus orbit-dependent
non-separable pairing model with two non-degenerate j-orbits is presented. The
extended one-variable Heine-Stieltjes polynomials associated to the Bethe
ansatz equations of the solution are determined, of which the sets of the zeros
give the solution of the model, and can be determined relatively easily. A
comparison of the solution to that of the standard pairing interaction with
constant interaction strength among pairs in any orbit is made. It is shown
that the overlaps of eigenstates of the model with those of the standard
pairing model are always large, especially for the ground and the first excited
state. However, the quantum phase crossover in the non-separable pairing model
cannot be accounted for by the standard pairing interaction.Comment: 5 pages, 1 figure, LaTe
