第一性原理研究氧在Ni(111)表面上的吸附能及功函数

采用基于密度泛函理论（DFT）广义梯度近似（GGA）下的第一性原理方法系统地研究了不同覆盖度下O在Ni（111）表面的吸附特性.计算结果表明，O在Ni（111）表面的稳定吸附位为三重面心立方（fcc）洞位，吸附能随着覆盖度的增加而减小，O诱导Ni（111）表面功函数的变化量与覆盖度成近线性关系，并随着覆盖度的增加而增大.同时,通过对电子密度和分波态密度的分析发现：O在Ni（111）表面的吸附使得Ni表面电子向O原子转移，形成表面偶极矩，导致功函数增加；表面Ni原子的3d轨道和O的2p轨道通过耦合、杂化作用形成成键态和反键态，而反键态几乎不被占据，因而O—Ni键相互作用比较强，吸附能较大.关键词：表面吸附密度泛函理论吸附能功函数

First-principles study of the adsorption energy and work function of oxygen adsorption on Ni(111) surface

The adsorption of atomic oxygen on the Ni（111） surface has been systematically investigated through first-principles DFT-GGA methods in wide ranges of coverage. It was found that the fcc hollow site is the energetically most favorable for the whole coverage range considered. The adsorption energy decreases with the coverage θ，while the work function increases linearly with the coverage.It can be also concluded from analysis of the electron density and projected density of states that the electron transfer from the substrate （Ni atoms） to the O atom gives rise to the appearance of a dipole moment, which results in a large increase in the work function. The O—Ni interaction between Ni 3d and O 2p orbitals results in the formation of bonding and antibonding states, while the antibonding states are hardly occupied. Therefore, the bonding interaction between O and Ni is stonger, and the adsorption energy is larger.