  Generalized seniority provides a truncation scheme for the nuclear shell
model, based on pairing correlations, which offers the possibility of
dramatically reducing the dimensionality of the nuclear shell-model problem.
Systematic comparisons against results obtained in the full shell-model space
are required to assess the viability of this scheme. Here, we extend recent
generalized seniority calculations for semimagic nuclei, the Ca isotopes, to
open-shell nuclei, with both valence protons and valence neutrons. The
even-mass Ti and Cr isotopes are treated in a full major shell and with
realistic interactions, in the generalized seniority scheme with one broken
proton pair and one broken neutron pair. Results for level energies, orbital
occupations, and electromagnetic observables are compared with those obtained
in the full shell-model space. We demonstrate that, even for the Ti isotopes,
significant benefit would be obtained in going beyond the approximation of one
broken pair of each type, while the Cr isotopes require further broken pairs to
provide even qualitative accuracy.
