  A canonical-basis formulation of the time-dependent Hartree-Fock-Bogoliubov
(TDHFB) theory is obtained with an approximation that the pair potential is
assumed to be diagonal in the time-dependent canonical basis. The
canonical-basis formulation significantly reduces the computational cost. We
apply the method to linear-response calculations for even-even nuclei. E1
strength distributions for proton-rich Mg isotopes are systematically
calculated. The calculation suggests strong Landau damping of giant dipole
resonance for drip-line nuclei.
