  We present the results of the modelling of CO adsorption and catalytic CO
oxidation on inhomogeneous Pt(100) surfaces which contain structurally
different areas. These areas are formed during the CO-induced transition from a
reconstructed phase with hexagonal geometry of the overlayer to a bulk-like
(1x1) phase with square atomic arrangement. In the present approach, the
surface transition is explained in terms of nonequilibrium bistable behavior.
The bistable region is characterized by a coexistence of the hexagonal and
(1x1) phases and is terminated in a critical bifurcation point which is located
at (T_c ~680 K, p_CO ~10 Torr). Due to increasing fluctuations, the behavior at
high temperatures and pressures in the vicinity of this cusp point should be
qualitatively different from the hysteresis-type behavior which is typically
observed in the experiments under ultrahigh vacuum conditions. On the
inhomogeneous surface, we find a regime of nonuniform oscillations
characterized by random standing waves of adsorbate concentrations. The
resulting spatial deformations of wave fronts allow to gain deeper insight into
the nature of irregular oscillations on Pt(100) surface.
