Department of Chemistry-Ångström, Uppsala University, Box 538, SE-751 21Uppsala, Sweden.
J Chem Phys. 2017 Feb 14;146(6):064703. doi: 10.1063/1.4971790.
In this work, a range of van der Waals type density functionals are applied to the HO/NaCl(001) and HO/MgO(001) interface systems to explore the effect of an explicit dispersion treatment. The functionals we use are the self-consistent vdW functionals vdW-DF, vdW-DF2, optPBE-vdW, optB88-vdW, optB86b-vdW, and vdW-DF-cx, as well as the dispersion-corrected PBE-TS and PBE-D2 methods; they are all compared with the standard PBE functional. For both NaCl(001) and MgO(001), we find that the dispersion-flavoured functionals stabilize the water-surface interface by approximately 20%-40% compared to the PBE results. For NaCl(001), where the water molecules remain intact for all overlayers, the dominant contribution to the adsorption energy from "density functional theory dispersion" stems from the water-surface interactions rather than the water-water interactions. The optPBE-vdW and vdW-DF-cx functionals yield adsorption energies in good agreement with available experimental values for both NaCl and MgO. To probe the strengths of the perturbations of the adsorbed water molecules, we also calculated water dipole moments and found an increase up to 85% for water at the MgO(001) surface and 70% at the NaCl(001) surface, compared to the gas-phase dipole moment.
在这项工作中，一系列范德华型密度泛函被应用于 HO/NaCl(001)和 HO/MgO(001)界面体系，以探索显式色散处理的效果。我们使用的泛函是自洽范德华泛函 vdW-DF、vdW-DF2、optPBE-vdW、optB88-vdW、optB86b-vdW 和 vdW-DF-cx，以及色散校正的 PBE-TS 和 PBE-D2 方法；它们都与标准 PBE 泛函进行了比较。对于 NaCl(001)和 MgO(001)，我们发现与 PBE 结果相比，色散修饰的泛函使水-表面界面稳定约 20%-40%。对于 NaCl(001)，其中所有覆盖层的水分子都保持完整，“密度泛函理论色散”对吸附能的主要贡献来自于水-表面相互作用，而不是水-水相互作用。optPBE-vdW 和 vdW-DF-cx 泛函得出的吸附能与 NaCl 和 MgO 的可用实验值非常吻合。为了探究吸附水分子的扰动强度，我们还计算了水分子的偶极矩，并发现与气相偶极矩相比，在 MgO(001)表面，水的偶极矩增加了 85%，在 NaCl(001)表面增加了 70%。
