Quantum Chemistry Investigation of the Size Effect About the Chemisorption of Ammonia On Aluminum Clusters

Through properly selecting the optimal geometries of the aluminum clusters, an approximate quantum chemistry method, i.e. Hartree-Fock-SCF CNDO/2 method, had been adapted in this paper to investigate the adsorption of ammonia on the aluminum clusters Al_n（n=1-13）, which includes all possible kinds of adsorption configuration. The results show the magic property of the adsorption intensities, that is, the adsorption energies of ammonia on Al₂, Al₆, Al₁₂ are especially large, which are in good agreement with the experimental results and that predicted by the electronic Shell Model. Further, the nature of such adsorption has also been discussed.