Yang Rui, Rendell Alistair P
Department of Computer Science, College of Engineering and Computer Science, The Australian National University, Canberra, ACT 0200, Australia.
J Phys Chem B. 2006 May 18;110(19):9608-18. doi: 10.1021/jp057391u.
The adsorption of Ga atoms in low coverage on the Al-terminated alpha-Al(2)O(3)(0001) surface has been studied theoretically by using first principles periodic boundary condition (PBC) calculations within the framework of the generalized gradient approximation (GGA). Eight possible adsorption sites are investigated, but only two are found to correspond to stationary points. Both of these locations are characterized as hollow sites, with three surrounding surface O atoms and an Al atom in the center located deeper within the Al(2)O(3) slab. The slight difference in the stability of these two sites is due to a difference in the chemical interactions between the Ga atom and the surface O atoms. Strong interactions between the Highest Occupied Molecular Orbital (HOMO) of the Ga atom and the surface state of the Al(2)O(3) surface are observed. This interaction promotes charge transfer from the Ga to the surface Al atoms, which in turn causes the surface Al atoms to move up from the surface.
通过在广义梯度近似（GGA）框架内使用第一性原理周期性边界条件（PBC）计算，从理论上研究了低覆盖度下Ga原子在以Al为终端的α - Al₂O₃(0001)表面上的吸附情况。研究了八个可能的吸附位点，但仅发现两个对应于驻点。这两个位置均被表征为空心位点，周围有三个表面O原子，中心有一个Al原子位于Al₂O₃平板内部更深的位置。这两个位点稳定性的细微差异是由于Ga原子与表面O原子之间化学相互作用的差异所致。观察到Ga原子的最高占据分子轨道（HOMO）与Al₂O₃表面态之间存在强相互作用。这种相互作用促进了电荷从Ga转移到表面Al原子，进而导致表面Al原子从表面向上移动。
