Roughening of chemically reacting interfaces

There has been much interest recently in simple lattice-gas models of catalytic reactions. Using Monte Carlo simulations, we investigate interfacial roughening in a model of a Langmuir-Hinshelwood reaction which includes an effective repulsive interaction between the two reacting species. We measure the width of the reactive zone between the two reactants and the roughness of this interface. It is found that, when the interspecies repulsive interaction is nonzero, the interface roughness obeys the scaling law w∼${\mathit{t}}^{\mathrm{\beta }}$, with β=1/4. When there is no interspecies interaction, the interface roughness scales as ${\mathit{t}}^{1/2}$. The reactive-zone width also scales as ${\mathit{t}}^{1/2}$ when there is no interspecies repulsion. With interspecies repulsion, however, we find that the reactive-zone width tends to a finite value at long times. We argue that in this case the interface should be described by the Kardar-Parisi-Zhang equation [Phys. Rev. Lett. 56, 889 (1986)] with ν≠0 and λ=0.