  Using our new numerical-relativity code SACRA, long-term simulations for
inspiral and merger of black hole (BH)-neutron star (NS) binaries are
performed, focusing particularly on gravitational waveforms. As the initial
conditions, BH-NS binaries in a quasiequilibrium state are prepared in a
modified version of the moving-puncture approach. The BH is modeled by a
nonspinning moving puncture and for the NS, a polytropic equation of state with
$\Gamma=2$ and the irrotational velocity field are employed. The mass ratio of
the BH to the NS, $Q=M_{\rm BH}/M_{\rm NS}$, is chosen in the range between 1.5
and 5. The compactness of the NS, defined by ${\cal C}=GM_{\rm NS}/c^2R_{\rm
NS}$, is chosen to be between 0.145 and 0.178. For a large value of $Q$ for
which the NS is not tidally disrupted and is simply swallowed by the BH,
gravitational waves are characterized by inspiral, merger, and ringdown
waveforms. In this case, the waveforms are qualitatively the same as that from
BH-BH binaries. For a sufficiently small value of $Q \alt 2$, the NS may be
tidally disrupted before it is swallowed by the BH. In this case, the amplitude
of the merger and ringdown waveforms is very low, and thus, gravitational waves
are characterized by the inspiral waveform and subsequent quick damping. The
difference in the merger and ringdown waveforms is clearly reflected in the
spectrum shape and in the "cut-off" frequency above which the spectrum
amplitude steeply decreases. When an NS is not tidally disrupted (e.g., for
Q=5), kick velocity, induced by asymmetric gravitational wave emission, agrees
approximately with that derived for the merger of BH-BH binaries, whereas for
the case that the tidal disruption occurs, the kick velocity is significantly
suppressed.
