  We present result of calculations of the surface phonon dispersion curves for
Pt(110) using density functional theory in the local density approximation and
norm conserving pseudopotentials in a mixed-basis approach. Linear response
theory is invoked and both the unreconstructed, and the missing row (1x2)
reconstructed surfaces are considered. We find that the reconstruction is not
driven by a phonon instability. Most of the observed phonon modes for the (1x2)
structure can be understood in terms of simple folding of the (1x1) Brillouin
zone onto that for the (1x2) surface. Largest changes in the phonon frequencies
on surface reconstruction occur close to the zone boundary in the (001)
direction. Detailed comparison of atomic force constants for the (1x1) and the
(1x2) surfaces and their bulk counterparts show that the bulk value is attained
after three layers. Our calculations reproduce nicely the Kohn anomaly observed
along the (110) direction in the bulk. We do not find a corresponding effect on
the surface.
