Neutron-proton interaction and bandcrossing in the cranking model

A cranked Hartree-Fock-Bogolyubov formalism for a description of collective rotational states, which includes the n-p residual interaction along with pairing and is applicable to a neutron-proton system is presented. A delta force form is used for the n-p residual interaction. A simple model is then developed where the valence neutrons and the valence protons occupy i13/2 and h11/2 orbitals, respectively. Results of these calculations are presented to show the effect of n-p interaction on the phenomenon of bandcrossing. Within the limits of such a restrictive model (which is particularly applicable to the (h11/2)p(i13/2)n bands in odd-odd nuclei) evidence is found for a shifting of the first bandcrossing frequency to a larger value. It is concluded that n-p interaction can also affect many other phenomena in the high spin region. (author). 6 figs., 44 refs