An ab initio molecular orbital study connected with adsorption experiments was performed to determine the mechanism of physical adsorption and chemical adsorption of C 2H 4 on metals, and to compare the effects of the two kinds of adsorption.The results indicated that the adsorption styles were determined by whether there were local symmetry-adapted orbitals, whether the energy gap between symmetry-adapted orbitals was small and whether the electron occupancy of the symmetry-adapted orbitals was “occupancy vs. vacancy”.The different valence shells and orbital energies of Ag + and Na + resulted in different adsorption styles,chemical adsorption of C 2H 4 on Ag + and physical adsorption of C 2H 4 on Na + respectively.
