A Practical Method for Determining the Cluster Model Size and the Estimation of the Energy Barrier on Heterogeneous Catalysts

Abstract

A practical method for determining the cluster model size and the estimation of the energy barrier on heterogeneous catalyst, In2O3(111) cluster, on which acetaldehyde is successively converted acetic acid and acetoacetic acid, has been proposed. The cluster size determination is executed as follows; 1) we determine the optimized adsorption structure of reactant, 2) we divide the structure into the reactant fragment and the cluster fragment, and calculate "Paired interacting orbitals (PIO)," 3) we determine the cluster size by using the atomic composition of the PIO of cluster fragment. The estimation of energy barrier is executed as follows; 1) we suppose a transition state, and assume a reactant side intermediate state (RTint), and a product side intermediate state (PDint), 2) we calculate PIOs of the RTint and those of the PDint and compare them, 3) we change the structures of RTint and PDint until the similarities of the PIOs are almost equal, 4) we calculate the total energies of both final intermediates, then, 5) we define an estimated barrier (Ebarriar) according to the following equation;Ebarrier = (ERTint.final +EPDint.final)/2 –Ereactant.