中文摘要：

利用基于密度泛函理论的第一性原理方法研究了Ni1-rPtx（111）和Ni1-xRtx（001）表面合金的功函数．计算结果表明，Pt原子掺杂在表面层时对功函数影响较大，而且表面层Pt原子掺杂后的舍金结构最为稳定；对于Ni1-xPtx（001），当表面层Pt原子的覆盖度从0增加到100％时，功函数近线性增加了0．6eV；而对于Ni1-rPtx（111），当表面层Pt原子的覆盖度从0增加到25％时，功函数增加了0．22eV，覆盖度从25％增加到100％时，功函数却几乎不再变化．上述结果表明，表面层合金化对功函数有重要影响，而金属功函数又强烈依赖于表面取向。

英文摘要：

Work functions of Nil-xPtx （111） and Nil-xPtx （001） surface alloys with differ- ent compositions are investigated using first-principles methods based on density-functional theory. Results of calculations reveal that Pt doping in the surface layer has a significant ef- fect on the work function and the alloy with Pt-doped in the surface layer is most stable. The work function of Nil-zPtx （001） surface increases linearly by as much as 0.6 eV when the surface coverage of Pt atoms increases from zero up to 100%, while that of Nil-xPtx （111） surface increases by only 0.22 eV when the surface coverage of Pt atoms increases from zero to 25%0 and hardly changes when the surface coverage of Pt atoms increases from 25% to 100%. The above results reveal that Surface alloying has a significant effect on the work function and the metal work function has strongly orientation dependence.