arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2007.04126physics.chem-phphysics.comp-ph
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S $_N$ 2反应的溶剂反应坐标

Solvent reaction coordinate for an S$_N$2 reaction

Christian Leitold, Christopher J. Mundy, Marcel D. Baer, Gregory K. Schenter, Baron Peters

摘要:

利用量子力学/分子力学(QM/MM)的计算机模拟方法,结合跃迁路径采样和惯性似然最大化,研究了水溶液中典型的SN 2反应Cl $^-$ + CH $_3$ Cl $\to$ CH $_3$ Cl + Cl $^-$.我们已经确定了一个新的溶剂坐标,以补充在经典分析中使用的原始原子交换坐标,由Erasekhar,Smith和Jorgensen [Ref 1]。新的溶剂坐标量化的瞬时溶剂诱导的极化相对于平衡平均电荷密度在每个点沿反应途径。的基础上的似然分数和提交人分布,新的溶剂坐标改善溶剂动力学效应相对于先前提出的溶剂坐标的描述。然而,它不增加透射系数或过渡态理论速率计算的准确性。

英文摘要:

We study the prototypical SN2 reaction Cl$^-$ + CH$_3$Cl $\to$ CH$_3$Cl + Cl$^-$ in water using quantum mechanics / molecular mechanics (QM/MM) computer simulations with transition path sampling and inertial likelihood maximization. We have identified a new solvent coordinate to complement the original atom-exchange coordinate used in the classic analysis by Chandrasekhar, Smith, and Jorgensen [Ref1]. The new solvent coordinate quantifies instantaneous solvent induced polarization relative to the equilibrium average charge density at each point along the reaction pathway. On the basis of likelihood scores and committor distributions, the new solvent coordinate improves upon the description of solvent dynamical effects relative to previously proposed solvent coordinates. However, it does not increase the transmission coefficient or the accuracy of a transition state theory rate calculation.

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