Calculation of the reaction of ethylene, propene, and acetylene on zeolite models

The reactions of ethylene, propene, and acetylene with two different zeolite models are computationally characterized using both semiempirical and ab initio methods. The MP2/6-31G* level calculations give activation energies which appear too high in comparison with the estimated experimental values. The DFT values seem more reasonable. The AM1 and PM3 transition state structures appear dubious with respect to both ab initio results and generally accepted intuitive descriptions.