AI 中文总结
本研究通过比较两种偏置方案的从头算分子动力学，解耦了表面电荷与电解质离子对Pt(111)界面水结构的影响，发现表面电荷主导平均响应，而离子效应仅在局部氢键拓扑和振动指纹中显现。
AI 中文摘要
已知带电金属电极处界面水的结构会影响电催化，实验也强调其对电解质离子种类和外加偏压的敏感性。为将通用的电荷控制的结构变化与离子特异性效应区分开来，我们比较了通过两种截然不同的偏置方案生成的带电Pt(111)处从头算分子动力学水结构：双电层中显式离子不平衡和均匀分布的部分带电氢原子。尽管这两种抗衡电荷表示方式不同，但在共同的表面电荷标度上进行比较时，两种方法对第一层水双分子层，特别是化学吸附的第一层，产生了一致的平均响应。与显式电解质离子相关的方法依赖性差异仅在更局部的结构描述符中显现。氢键拓扑揭示了电荷依赖的链状到环状的重排，其中显式离子在零电荷电位附近增强了环状结构的占比。层分辨的振动态密度（VDOS）将最强的O-H伸缩扰动归属于化学吸附的第一层水，并识别出离子配位水的高频特征，而计算的振动和频生成（VSFG）光谱表明，物理吸附的、面向电解质的区域对抗衡电荷表示方式特别敏感。这些结果表明，表面电荷控制平均结构响应，而电解质离子及其溶剂化壳层仅在研究或探测局部精细描述符（例如界面双分子层的氢键网络拓扑和振动指纹）时才显现。
英文摘要
The structure of interfacial water at electrified metal electrodes is known to affect electrocatalysis, and experiments highlight its sensitivity to electrolyte ion identity and applied bias. To disentangle generic charge-controlled structural changes from ion-specific effects, we compare ab initio molecular dynamics water structures at electrified Pt(111) generated with two very different biasing schemes: an explicit ion imbalance in the double layer and homogeneously distributed partially charged hydrogen atoms. Despite these distinct counter-charge representations, both approaches yield a consistent average response of the first water bilayer, in particular of the chemisorbed first layer, when compared on a common surface-charge scale. Method-dependent differences, in particular those associated with explicit electrolyte ions, become apparent only in more local structural descriptors. The hydrogen-bond topology reveals charge-dependent chain-to-ring rearrangements, with explicit ions enhancing ring populations near the potential of zero charge. Layer-resolved vibrational density of states (VDOS) assigns the strongest O-H stretching perturbation to chemisorbed first-layer water and identifies high-frequency signatures of ion-coordinated water, while computed vibrational sum-frequency generation (VSFG) spectra show that the physisorbed, electrolyte-facing region is particularly sensitive to the counter-charge representation. These results suggest that surface charge controls the average structural response, whereas electrolyte ions and their solvation shells become visible only when locally refined descriptors are investigated or probed, e.g. the H-bond network topology and vibrational fingerprints of the interfacial bilayer.
Comments32 pages, 5 figures, 1 table. Supporting Information (14 pages, 14 figures, 1 table) appended
