Phase diagram of dimer - trimer model on square and hexagonal lattices: a Monte Carlo simulation study

We have a model for heterogeneous catalysis in which dimer A/sub 2/ and trimer B/sub 3/are chemisorbed on to a square lattice (each site has four nearest neighbors) as well as hexagonal lattice (each site has six nearest neighbors). Nearest adsorbed A and B react and desorb, leaving vacant sites. Kohler and Avraham have also studied this reaction on a hexagonal lattice. We have found number of discrepancies with their results. The effect of change of lattice co-ordination number on the phase diagram of the model is studied by computer simulation. A phase diagram is observed which is qualitatively similar to the shown by Kohler and Avraham. However, steady reactive window width is very small and values of coverage and production rate are quantitatively different from those obtained for hexagonal lattice. (author)