Shell-model operator for KJ-band splitting in odd-A nuclei
A shell-model operator is introduced that generates Kj-band splitting in odd-A nuclei, where KJ=KL+KS is the projection of the total angular momentum, J = L+S, on the principal symmetry axis of the system. An expression is given for the matrix elements of this K2J operator in angular-momentum-projected and spin-coupled basis states of the SU(3) scheme. Eigenvalues of the K2J operator in the leading normal-SU(3) symmetry for 25Mg and the leading pseudo-SU(3) symmetries for 159Dy and 165Fr are compared with the corresponding quantum rotor results. Shell-model results for the ds-shell nucleus21Ne with 17O single-particle energies and only the three residual interactions Q·Q,J2 and K2J are shown to compare favorably with experiment and an analysis based on a realistic (renormalized two-body form fit to experimental data) ds-shell interaction. The K2J operator is also the appropriate form for integral S≠0 configurations in even-A nuclei with matrix elements that reduce to those of the previously defined K2L operator in S = 0 states. © 1992.