Clabaut Paul, Fleurat-Lessard Paul, Michel Carine, Steinmann Stephan N
Univ. Lyon, ENS de Lyon, CNRS UMR 5182, Université Claude Bernard Lyon 1, Laboratorie de Chimie, 46 allée d'Italie, F-69364 Lyon, France.
Institut de Chimie Moléculaire de l'Université de Bourgogne (ICMUB), UMR CNRS 6302, Université de Bourgogne Franche-Comté (UBFC), 9 avenue Alain Savary 21078 Dijon, France.
J Chem Theory Comput. 2020 Jul 14;16(7):4565-4578. doi: 10.1021/acs.jctc.0c00091. Epub 2020 Jun 2.
Understanding the structure of the water/metal interfaces plays an important role in many areas ranging from surface chemistry to environmental processes. The size, required phase-space sampling, and the slow diffusion of molecules at the water/metal interfaces motivate the development of accurate force fields. We develop and parametrize GAL19, a novel force field, to describe the interaction of water with two facets (111 and 100) of five metals (Pt, Pd, Au, Ag, Cu). To increase transferability compared to its predecessor GAL17, the water-metal interaction is described as a sum of pairwise terms. The interaction energy has three contributions: (i) physisorption is described via a Tang and Toennies potential, (ii) chemisorption and surface corrugation rely on an attractive Gaussian term, and (iii) the angular dependence is explicitly included as a truncated Fourier series. Thirteen parameters are used for each metal surface and were fitted on 250 water adsorption energies computed at the PBE+dDsC level. The performance of GAL19 was evaluated on a set of more than 600 DFT adsorption energies for each surface, leading to an average root-mean-square deviation of only 1 kcal/mol, correctly reproducing the adsorption trends: strong on Pt and Pd but weaker on Ag, Au, and Cu. This force field was then used to simulate the water/metal interface for all ten surfaces for 1 ns. Structural analyses reveal similar tendencies for all surfaces: a first, dense water layer that is mostly adsorbed on the metal top sites and a second layer up to around 6 Å, which is less structured. On Pt and Pd, the first layer is strongly organized with water lying flat on the surface. The pairwise additive functional form allows one to simulate the water adsorption on alloys, which is demonstrated at the example of Ag/Cu and Au/Pt alloys. The water/Ag-Cu interface is predicted to be disordered with water mostly adsorbed on Cu which should exacerbate the Ag reactivity. On the contrary, incorporating Pt into Au materials leads to a structuring of the water interface. Our promising results make GAL19 an ideal candidate to get representative sampling of complex metal/water interfaces as a first step toward accurate estimation of free energies of reactions in solution at the metal interface.
理解水/金属界面的结构在从表面化学到环境过程的许多领域中都起着重要作用。水/金属界面处分子的尺寸、所需的相空间采样以及缓慢的扩散促使人们开发精确的力场。我们开发并参数化了一种新型力场GAL19，用于描述水与五种金属（Pt、Pd、Au、Ag、Cu）的两个晶面（111和100）之间的相互作用。为了比其前身GAL17具有更高的可转移性，水-金属相互作用被描述为成对项的总和。相互作用能有三个贡献：（i）物理吸附通过Tang和Toennies势来描述，（ii）化学吸附和表面起伏依赖于一个吸引性的高斯项，（iii）角度依赖性被明确包含为一个截断的傅里叶级数。每个金属表面使用13个参数，并根据在PBE + dDsC水平计算的250个水吸附能进行拟合。GAL19的性能在每个表面一组超过600个DFT吸附能上进行了评估，导致平均均方根偏差仅为1 kcal/mol，正确地再现了吸附趋势：在Pt和Pd上较强，但在Ag、Au和Cu上较弱。然后使用这个力场对所有十个表面的水/金属界面进行了1 ns的模拟。结构分析揭示了所有表面的相似趋势：第一层是密集的水层，大多吸附在金属顶位，第二层延伸至约6 Å，结构较少。在Pt和Pd上，第一层排列紧密，水平躺于表面。成对加和函数形式允许模拟水在合金上的吸附，这在Ag/Cu和Au/Pt合金的例子中得到了证明。预计水/Ag-Cu界面是无序的，水大多吸附在Cu上，这应该会加剧Ag的反应性。相反，将Pt掺入Au材料中会导致水界面的结构化。我们的 promising 结果使GAL19成为获取复杂金属/水界面代表性采样的理想候选者，这是朝着准确估计金属界面溶液中反应自由能迈出的第一步。 （注：原文中“promising”未翻译，可能是原文有误，推测应为“promising”，意为“有前景的”）
