从空水辅助机制计算天然气水合物中的甲扩散率的路径采样计算
Baron Peters1, Nils E R Zimmermann, Gregg T Beckham
1Centre Europeen de Calcul Atomique et Moleculaire, Ecole Normale Superieure, 46, Allee d'Italie, 69364 Lyon, France. baronp@engineering.ucsb.edu
Journal of the American Chemical Society
|December 5, 2008
概括
本研究使用先进的模拟来估计天然气水合物中的甲扩散性. 甲运输受到子连接和空水辅助扩散机制的限制,显示出比先前预测的速度慢.
科学领域:
- 物理化学 物理化学
- 材料科学 材料科学 材料科学
- 计算化学计算化学
背景情况:
- 由于实验的挑战,估计天然气水合物中的运输特性至关重要.
- 在水合物中的甲扩散对于理解水合物形成和分解至关重要.
研究的目的:
- 为了估计一个结构中的甲扩散性,我用气化水晶.
- 为了阐明水合物中甲扩散的机制.
主要方法:
- 使用平衡路径采样用于自由能量计算.
- 利用反应性流量和动力蒙特卡洛模拟.
- 计算速度常数来模拟自我扩散.
主要成果:
- 确定了甲的缺水辅助扩散机制.
- 对涉及五个水环的扩散途径观察到高能障碍.
- 由于格子结构和子偏好,甲的自我扩散速度比爱因斯坦估计的要慢.
结论:
- 均衡路径采样对于计算超出雨采样范围的自由能量是有效的.
- 为水合物中的甲提供了关键的运输属性估计.
- 在250K时估计的甲扩散率 (D) 约为7×10×15×m×2/s.
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