论文标题
高温反应可以通过最小能量路径模型描述吗？空间障碍很重要
Can High-Temperature Reactions Be Described by a Minimum Energy Path Model? Steric Hindrance Matters
论文作者
论文摘要
高温反应在自然界中广泛存在。但是，它们很难在实验或计算上被表征。化学反应计算模型中常规使用的最小能路径（MEP）模型没有合理地描述高温反应，因为高能结构在那里积极参与。在这项研究中，以Cu（111）表面上的CH4分解为例，我们将MEP的结果与在不同温度下通过Ab Intibal Molecular Dynamics（AIMD）模拟明确采样所有相关结构获得的MEP结果。有趣的是，我们发现，对于受强部障碍效应保护的反应，即使在接近Cu熔点的温度下，MEP仍然有效地遵循。相比之下，没有这种保护，表面Cu原子的柔韧性会导致高温下显着的自由屏障降低。因此，应重新审视有关基于MEP计算的石墨烯生长机制的一些结论。这项研究提供的物理见解可以加深我们对高温表面反应的理解。
High-temperature reactions widely exist in nature. However, they are difficult to be characterized either experimentally or computationally. The routinely used minimum energy path (MEP) model in computational modeling of chemical reactions is not justified to describe high-temperature reactions since high-energy structures are actively involved there. In this study, using CH4 decomposition on the Cu(111) surface as an example, we systematically compare MEP results with those obtained by explicitly sampling all relevant structures via ab initio molecular dynamics (AIMD) simulations at different temperatures. Interestingly, we find that, for reactions protected by a strong steric hindrance effect, the MEP is still effectively followed even at a temperature close to the Cu melting point. In contrast, without such a protection, the flexibility of surface Cu atoms can lead to a significant free energy barrier reduction at a high temperature. Accordingly, some conclusions about graphene growth mechanisms based on MEP calculations should be revisited. Physical insights provided by this study can deepen our understanding on high-temperature surface reactions.
