本文用EHMO法研究了在七铁原子簇活性中心模型上氮的活化和加氢机理。计算表明,在所考虑的四种吸附模型中,以横卧吸附的N_2侧面加氢能量上最有利。表面吸附的N原子和H原子也可直接结合生成NH基。计算还表明,气相N_2与吸附H有直接作用的可能性。吸附N_2(或N)征加氢过程中要克服一位垒。在过渡态,吸附H的电性从H~(δ-)转为H~(δ+),同时发生N—H强成键作用。 In this paper, the activation and hydrogenation mechanism of nitrogen on the active center model of seven iron cluster has been studied by EHMO method. Calculations show that in the four adsorption models considered, it is most advantageous to hydrogenate the side of N2 adsorbed by horizontal adsorption. N atoms and H atoms adsorbed on the surface may also be directly combined to form an NH group. The calculation also shows that there is a possibility that the gas phase N 2 can directly adsorb H. Adsorption N_2 (or N) levy sign of hydrogen to overcome a barrier. In the transitional state, the electrical property of adsorbed H is changed from H ~ (δ-) to H ~ (δ +), and strong N-H bond is formed at the same time.