STUDY OF DAMAGE SPREADING IN DIMER-DIMER IRREVERSIBLE SURFACE-REACTION MODELS

The spreading of globally distributed damage was studied in two variants of an irreversible dimer-dimer surface reaction model of the type 1/2 A(2) + B-2 --> B(2)A. The first model (model M1) 2 neglects desorption of B-2. On the contrary, the second version (model M3) takes this process into account. Both models exhibit irreversible (kinetic) phase transitions (IPT) from a reactive state with sustained production of B(2)A molecules to surface poisoned states without B(2)A production. Model M1 has a zero-width reaction window with a single critical point at which damage spreading is observed. For model M3 the damage also spreads and exhibits an abrupt discontinuity at the critical point where a continuous IPT from the poisoned state to the reactive regime is observed. Damage healing was only observed when M3 can be mapped onto a simple adsorption-desorption process of B-2. Close to the chaotic-frozen transition the order parameter critical exponent was found to be beta congruent to 1.075 +/- 0.019.