H,O原子在过渡金属表面吸附能的规则性

用Allan的简化d带模型描叙过渡金属的表面电子态,用广义相移法计算吸附原子在表面的吸附能,结果表明,不仅很好地描绘了H,O在一个周期的过渡金属表面吸附能的变化趋势,而且所算得的吸附原子感应的分离能级也同紫外光发射谱的实验符合得很好;同时还指出,简单气体在过渡金属表面的吸附能呈现规则性变化主要决定于费密能级E_F与吸附原子的有效能级ε_a之差(E_F-ε_a),其次是转移矩阵元ν和能带宽度w_b。关键词：

A SIMPLE THEORY FOR UNDERSTANDING THE REGULARI- TY OF CHEMISORPTION ENERGY OF SIMPLE GASES ON TRANSITION METALS

We presented a method for calculating the chemisorption energy of simple gases on transition metals series. The simplified d-band model of Allan has been applied to describe the electronic structure of transition metal surface, and the chemisorption energy is calculated by making use of the generalized phase shifts. The method is employed to study the adsorption of hydrogen and oxygen on 3d and 4d transition metals. The calculated results of the chemisorption energies show remarkable systematic trends, in good agreement with experiment. The calculated adsorbate induced electronic energy level [also being referred to as the split-off energy] is at approximately 6 eV below Fermi energy, that is comparable to UPS experiments. The conclusion deduced from the calculation is as follows: the difference between the Fermi level and effective adsorbed energy level (E_F-ε_a.) plays the crucial role in determining the trends in the chemisorption energy, the variation in the bandwidth across the series and the adatom-metal atom transfer matrix element ν are of secondary importance.