Ni（111）（√3×√3）R30°表面吸附Sn和Pb的第一性原理研究

Sn and Pb adsorption on Ni（111）（√3×√3）R30° surface： A density functional theory study

用第一性原理的自旋密度泛函理论计算了Sn和Pb吸附在Ni（111）（√3×√3）R30°表面的几何构型和功函变化。能量计算表明Sn和Pb吸附在（111）（√3×√3）R30°表面形成的最稳定相均是替代吸附，并不存在类似于Sb吸附于Cu（111）（√3×√3）R30°和Ag（111）（√3×√3）R30°。表面时形成的层错现象，验证了以前的实验结果。对于Sn和Pb吸附在Ni（111）（√3×√3）R30°表面形成的最稳定表面合金相，表面弛豫效应都不明显，皱褶幅度分别为0．0548和0．0987nm，都比硬球模型所预言的小，表明Sn-Ni和Pb-Ni金属键含有大量的共价键成分。计算所得的几何参数与实验符合得很好。Sn和Pb在Ni（111）（√3×√3）R30°表面吸附前后的功函变化值分别为0．38和0．433eV，表示电荷均从底物移向吸附物。

The geometry property and work-function change of Sn and Pb adsorption on Ni（111）（√3×√3）R30° surface were investigated by using the density functional theory method of first-principles. Total energy calculations show that substitutional surface alloy phases in the outermost layer are preferable for Sn and Pb adsorption on Ni（111）（√3×√3）R30° surface, and they have no stacking fault like that found for similar phases of Sb on Cu（111） and Ag（111）. It confirmed the earlier experiments. In the case of the most stable surface alloy phases for Sn and Pb adsorption on Ni（111）（√3×√3）R30° surface, the relaxation effects are marginal and the rumpling magnitudes are 0.0548 and 0.0987nm, respectively. They are smaller than the predictions from hard-sphere model, indicating of the covalent character in the bonds of Sn-Ni and Pb-Ni. Main structural parameters from experimental results are reproduced by our calculations. The changes of work-function due to Sn and Pb adsorption were found to be 0.38 and 0.43 eV for the Ni（111）（√3×√3）R30° surface, respectively. It shows that the charge is transformed from the substrate to the adsorbates.