  Properties of density-dependent contact pairing interactions in nuclei are
discussed. It is shown that the pairing interaction that is intermediate
between surface and volume pairing forces gives the pairing gaps that are
compatible with the experimental odd-even mass staggering. Results of the
deformed Hartree-Fock-Bogoliubov calculations for this `mixed' pairing
interaction, and using the transformed harmonic oscillator basis, are
presented.
