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本文采用改进的LEPS势研完Ni、Cu、Mn、Ni—Cu和Ni—Mn表面H_2化学吸附问题。首先用EHMO方法计算H原子与金属表面三个特殊位置1CN、3CN和4CN位置的作用势能曲线。对双金属采用虚晶近似进行同样的计算。而后用Morse函数拟合这些曲线,得出相应位置的Morse函数的参数D,α和r_0的值。再根据表面周期性的特点,用Fourier展开的前五项表示D,α和r_0随表面位置的变化,最后用LEPS势函数作出H_2在晶体(111)面上的吸附势能面。比较不同势能面的结构特点,说明Ni和Ni—Mn对H_2以3CN空穴吸附为主,而Cu和Ni—Cu则以1CN顶位吸附为主。并对相应的实验事实给予一定的解释。
In this paper, improved LEPS potential research finished Ni, Cu, Mn, Ni-Cu and Ni-Mn surface H 2 chemisorption problem. EHMO method is used to calculate the potential energy curves of the three specific positions of H atom and metal surface at 1CN, 3CN and 4CN positions. The same calculation is performed on the bimetal using the imaginary approximation. The Morse function is then used to fit the curves to obtain the values of the parameters D, α and r_0 of the Morse function for the corresponding position. According to the characteristics of the surface periodicity, the first five terms of Fourier expansion represent the changes of D, α and r_0 with the surface position. Finally, the potential energy surface of H_2 on the (111) plane of the crystal is obtained by LEPS potential function. The structural characteristics of different potential energy surfaces are compared. It is shown that Ni and Ni-Mn mainly adsorb HNO 3 to holes at 3CN sites, while Cu and Ni-Cu dominate at the top sites of 1CN. And give some explanation to the corresponding experimental facts.