One-quasiparticle states in the nuclear energy density functional theory

We study one-quasiproton excitations in the rare-earth region in the framework of the nuclear density functional theory in the Skyrme-Hartree-Fock-Bogoliubov variant. The blocking prescription is implemented exactly, with the time-odd mean field fully taken into account. The equal filling approximation is compared with the exact blocking procedure. We show that both procedures are strictly equivalent when the time-odd channel is neglected and discuss how nuclear alignment properties affect the time-odd fields. The impact of time-odd fields on calculated one-quasiproton band-head energies is found to be rather small, of the order of 100-200 keV; hence, the equal filling approximation is sufficiently precise for most practical applications. The triaxial polarization of the core induced by the odd particle is studied. We also briefly discuss the occurrence of finite-size spin instabilities that are present in calculations for odd-mass nuclei when certain Skyrme functionals are employed.