Department of Physics, University of Washington,
Seattle, Washington 98195-1560
Surface roughening induces a simultaneous deconstruction transition
in missing row reconstructed (110) facets of FCC crystals.
This transition can be described by the 4-state chiral clock-step model.
Numerical finite size scaling results indicate that at zero chirality
this transition has the character of a super imposed
Kosterlitz-Thouless type roughening and Ising type deconstruction transition.
A symmetry property of the model, called S-T invariance,
and related to super symmetry, elucidates this aspect.
In the strong chirality limit a fermion analysis applies.
The full phase diagram can be constructed by
combining these numerical and analytical results.
Pt(110) and Au(110) follow specific paths through it.
The only path consistent with the current experimental evidence
for Pt(110) is a roughening induced simultaneous deconstruction transition,
which has the character of an incommensurate melting transition
with respect to the reconstruction degrees of freedom.
This implies that the difference in energy between
clockwise and anti-clockwise steps is small in Pt(110).