通用框架用于将离子传输分解为可解释的机制
Universal Framework for Decomposing Ionic Transport into Interpretable Mechanisms
AI总结：
本文提出了一种通用框架，通过分析MD轨迹分解离子传输机制，量化传输过程，揭示不同机制的主导作用及活化能，为设计高性能离子导体提供理论指导。
摘要：
理解本征材料中离子传输的机制对于设计下一代离子导体用于能量存储设备至关重要，然而利用全原子分子动力学（MD）的研究大多仅限于报告总体传输系数，而没有对'如何携带电荷'进行定量、时空解析的分解。我们提出了一种计算框架，通过分析MD轨迹来定量解释宏观传输，将其分解为由物理驱动事件的加性贡献。这些定义要么通过启发式识别的微观转换来捕捉单离子跳跃、多离子跳跃和车辆运动等事件，要么通过化学可解释的配位宏观状态之间的转换。该框架的构建保证了归因贡献恰好等于通过Green-Kubo/爱因斯坦公式估计的Onsager传输系数，同时扫描采样窗口会揭示不同传输机制出现和主导的特征时间尺度。应用于三种典型的电解质——无机晶体、液体和聚合物——该框架定量解决了长期存在的争议（例如协同运动和交换的作用），识别了主导机制和限制步骤，量化了它们的频率和有效性，并提取了不同传输模式的活化能，从而提炼出快速传导的设计规则。这种通用且可重复的分析工具将MD轨迹转化为定量机制图，使离子导体社区能够裁定机制假设并加速发现。
英文摘要：
Understanding mechanisms of ion transport in bulk materials is central to designing next-generation ion conductors for energy storage devices, yet studies employing all-atom molecular dynamics (MD) have largely been limited to reporting overall transport coefficients without a quantitative, spatiotemporally resolved breakdown of \emph{how} charge is carried. We present a computational framework that analyzes MD trajectories to quantitatively interpret macroscopic transport by decomposing it into additive contributions from physically motivated events. They are defined either through heuristically identified microscopic transitions, capturing events such as single-ion hops, multi-ion hops, and vehicular motion, or through transitions between chemically interpretable coordination macrostates. The construction guarantees that attributed contributions sum exactly to the Onsager transport coefficients estimated via the Green-Kubo/Einstein formalism, while scanning the sampling window exposes characteristic temporal scales at which distinct transport mechanisms emerge and dominate. Applied across three prototypical electrolytes-inorganic crystals, liquids, and polymers-the framework quantitatively resolves long-standing debates (e.g., the role of concerted motion and exchange), identifies dominant mechanisms and rate-limiting steps, quantifies their frequencies and effectiveness, and extracts activation energies for distinct transport modes, thereby distilling design rules for fast conduction. This general and reproducible analysis tool turns MD trajectories into quantitative mechanism maps, enabling the ion-conductor community to adjudicate mechanistic hypotheses and accelerate discovery.
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