有限温度字符串与顺序参数作为分子晶体的集体变量:在外部电场下的TNT多态转换的一个案例
Shi-Jie Niu1,2, Fu-De Ren1
1School of Chemistry and Chemical Engineering, North University of China, Taiyuan 030051, China.
Molecules (Basel, Switzerland)
|June 19, 2024
概括
外部电场可以控制分子晶体的多态性,这对材料科学至关重要. 这项研究揭示了电场如何改变TNT晶体的转变路径,从而实现有针对性的多态变化.
科学领域:
- 材料科学 材料科学 材料科学
- 物理化学 物理化学
- 计算化学计算化学
背景情况:
- 分子晶体的多态转化对于能源储存等行业至关重要,但在分子层面上了解甚少.
- 众所周知,外部电场会影响这些转换,但其确切的机制尚不清楚.
研究的目的:
- 研究分子晶体中电场诱导的多态变化的分子水平机制.
- 探索使用订单参数 (OPs) 和K-means集群与有限温度字符串 (FTS) 模拟来研究这些转换.
- 阐明外部电场如何影响平均力 (PMF) 的潜力,并控制转换的方向性.
主要方法:
- 建立了基于分子间和分子方向的两种类型的顺序参数 (OP).
- 用于在不同电场下进行OP采样和有限温度串 (FTS) 模拟的K-平均集群.
- 计算了平均力 (PMF) 的潜力,以分析 ortho- (o-TNT) 和 meta- (m-TNT) 三二烯之间的多态过渡的能量格局.
主要成果:
- 外部电场降低了多态转换的能量障碍,减少了o-TNT和过渡状态之间的PMF差异.
- 与c轴平行的电场显著影响了PMF差异,变化与场强度相关.
- 虽然电场并没有加速融合,但减少了整体转换时间,并使从o-TNT到m-TNT的方向转换成为可能,同时阻碍了相反的情况.
结论:
- 该研究成功地证明了FTS与K-means聚类相结合的有效性,用于在电场下分析分子晶体多态.
- 外部电场可以通过影响双极时刻和核化动力学等因素来控制TNT晶体中多态转换的方向.
- 这项研究提供了分子层面的理解和一种可控制的方法来操纵分子晶体多态性,这对能量材料的生产和性能有影响.
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