Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996-1600, USA.
J Phys Chem A. 2011 Jun 30;115(25):7112-9. doi: 10.1021/jp1124316. Epub 2011 Apr 7.
We develop a model, based on pairwise additive He-Mg and He-O interactions, for the potential energy of He adsorbates above a rigid MgO(100) surface. The attractive long-range He-Mg and He-O interactions are assumed to have the form C(6)/r(6), with the C(6) coefficients determined from atomic data within the context of the Slater-Kirkwood approximation. The repulsive short-range He-Mg and He-O interactions are assumed to have the form C(p)/r(p), with the exponent p and the C(p) coefficients taken as adjustable parameters. We find that for p = 9, the C(p) coefficients can be chosen so that the laterally averaged He-MgO(100) pairwise additive interaction supports low-lying selective adsorption states, some of whose energies agree very well with the states' apparent energies inferred from experimental measurements. However, for realistic values of the adjustable parameters that define our model, the lateral corrugation of the model pairwise additive He-MgO(100) potential energy surface far exceeds the corrugation that has been inferred both from experimental measurements and from density functional calculations of the short-range He-MgO(100) interaction.
我们基于 He-Mg 和 He-O 相互作用的两两附加模型，开发了一种用于刚性 MgO(100) 表面上方 He 吸附物势能的模型。假设具有 C(6)/r(6)形式的长程吸引力 He-Mg 和 He-O 相互作用，其中 C(6)系数是根据 Slater-Kirkwood 近似范围内的原子数据确定的。假设短程排斥性 He-Mg 和 He-O 相互作用具有 C(p)/r(p)形式，其中指数 p 和 C(p)系数是可调参数。我们发现，对于 p = 9，我们可以选择 C(p)系数，使得横向平均的 He-MgO(100)两两附加相互作用支持低能选择性吸附态，其中一些能量与实验测量推断的状态的表观能量非常吻合。然而，对于定义我们模型的可调参数的实际值，模型的横向 He-MgO(100)相互作用的附加势能表面的波纹度远远超过了从实验测量和短程 He-MgO(100)相互作用的密度泛函计算推断出的波纹度。
