Cl^(-)在α-Al_(2)O_(3)表面吸附的驰豫方式和溶剂化模型选择

Relaxation method and solvation model of adsorption of Cl^(-)onα-Al_(2)O_(3)surface

采用基于密度泛函理论的第一性原理方法,研究了模型弛豫方式和隐式溶剂化模型的使用对α-Al_(2)O_(3)(0001)表面初始结构和Cl^(-)在表面吸附行为的影响.结果表明,在VASPsol方法模拟的水溶液环境下,全弛豫的α-Al_(2)O_(3)(0001)模型最上侧两个原子层的层间距变化量分别为-66.0%和+7.7%,更接近于实验值的-51%、+16%.Cl^(-)在液相表面上有着更低的吸附能,更容易与表面发生相互作用.相对于全弛豫的方法,固定底层6层原子的方式对α-Al_(2)O_(3)(0001)的表面结构、Cl^(-)在表面的吸附能、吸附距离以及表面原子bader电荷的变化量均造成了一定的影响.此工作将为α-Al_(2)O_(3)(0001)表面的点蚀研究提供可参照的前期结果和部分参数设置依据.

Effects of model relaxation methods and solvation model on the initial structure ofα-Al_(2)O_(3)(0001)surface and the adsorption behavior of Cl^(-)on the surface have been investigated using first-principles calculation method based on density functional theory.The results show that under the solvent environment simulated by the method of VASPsol,the variations of the interlayer spacing in the top two atomic layers on fully relaxedα-Al_(2)O_(3)(0001)surface are-66.0%and+7.7%,respectively,which is close to the experimental values of-51%and+16%.In aqueous environment,Cl^(-)has lower adsorption energies on the surface.Compared with the results of fully relaxation model,the surface structure ofα-Al_(2)O_(3)(0001),the adsorption energy and distance of Cl^(-)on the surface,the bader charge of surface atoms are all changed as the bottom six layers of atoms are fixed.This work aims to provide some parameters setting basis and preliminary results for the study of surface pitting onα-Al_(2)O_(3)(0001).