解析能量分子钙钛矿中对抗性碰撞控制反应性
Unraveling Antagonistic Collision-Controlled Reactivity in Energetic Molecular Perovskites with Deep Potential Molecular Dynamics
AI总结：
通过深度势分子动力学模拟揭示能量分子钙钛矿中碰撞控制反应性原理，解释不同阳离子对材料稳定性和反应性的影响。
摘要：
精确调控爆炸材料中化学分解的过程，无论是快速点火还是稳定耐久，需要指导反应性的原子尺度原理，这些原理仍然模糊不清。本文通过深度势分子动力学（DPMD）模拟解决了这一挑战，揭示了能量分子钙钛矿中普遍的碰撞控制原理，在（H₂dabco)B(ClO₄)₃中，H₂dabco²⁺=1,4-二氮双环[2.2.2]octane-1,4-二阳离子，B=Na⁺，K⁺，Rb⁺，NH₄⁺分别对应DAP-1，DAP-2，DAP-3和DAP-4。对超过100皮秒轨迹的原子尺度模拟结合阿伦尼乌斯拟合发现，增加B位离子半径（Na⁺<K⁺<Rb⁺）同时降低了活化能Eₐ，从而增强反应性，以及预指数因子A，抑制氢转移在位X和位A之间的碰撞概率，具有明显相反的动能后果。这种二元性很好地解释了基于K⁺的DAP-2的峰值稳定性和不敏感性，其最佳平衡热耐久性和碰撞耗散。对于基于铵的DAP-4，尽管NH₄⁺的半径接近K⁺，但反应性B位阳离子触发质子转移促进C-H键断裂。通过将静态阳离子半径与动态Eₐ-ln(A)耦合，我们解释了非单调分解温度（K⁺>NH₄⁺>Rb⁺>Na⁺）的宏观稳定性，并建立了通用能量材料设计的基础。
英文摘要：
The precise regulation of chemical decompositions in energetic materials, whether towards rapid ignition or stable endurance, requires atomic-scale principles governing reactivity, which remain elusive yet. Herein, we resolve this challenge through deep potential molecular dynamics (DPMD) simulations, uncovering a universal collision-control principle in energetic molecular perovskites, $\text{(H}_{2}\text{dabco)B(ClO}_{4}\text{)}_{3}$, where $\text{H}_{2}\text{dabco}^{2+}$ = 1,4-diazabicyclo[2.2.2]octane-1,4-diium, B = $\text{Na}^{+}$, $\text{K}^{+}$, $\text{Rb}^{+}$, $\text{NH}_{4}^{+}$ for DAP-1, DAP-2, DAP-3 and DAP-4, respectively. Atomic-scale simulation with Arrhenius fitting for over 100-ps trajectories reveals that increasing B-site ionic radius ($\text{Na}^{+} < \text{K}^{+} < \text{Rb}^{+}$) simultaneously reduces both activation energy $E_{a}$, which enhances reactivity, and pre-exponential factor $A$ which suppresses collision probabilities for hydrogen transfer between site $X$ and site $A$, with sharply opposing kinetic consequences. This duality well explains the peak stability and insensitivity in $\text{K}^{+}$-based DAP-2, which optimally balance thermal endurance and collision dissipation. For ammonium-based DAP-4, though the radius of $\text{NH}_{4}^{+}$ is close to $\text{K}^{+}$, the reactive B-site cation triggers proton transfer that promotes $\text{C-H}$ bond rupture. By linking static cation radii to dynamic $E_{a}$-ln$(A)$ coupling, we rationalize non-monotonic decomposition temperatures ($\text{K}^{+} > \text{NH}_{4}^{+} > \text{Rb}^{+} > \text{Na}^{+}$) macroscopic stability and establishes cornerstones for universal energetic material design.
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