Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716, USA.
J Phys Chem A. 2010 Mar 18;114(10):3556-68. doi: 10.1021/jp9090415.
Copper ions play crucial roles in many enzymatic and aqueous processes. A critical analysis of the fundamental properties of copper complexes is essential to understand their impact on a wide range of chemical interactions. However the study of copper complexes is complicated by the presence of strong polarization and charge transfer effects, multiple oxidation states, and quantum effects like Jahn-Teller distortions. These complications make the experimental observations difficult to interpret. In order to provide a computationally inexpensive yet reliable method for simulation of aqueous-phase copper chemistry, ReaxFF reactive force field parameters have been developed. The force field parameters have been trained against a large set of DFT-derived energies for condensed-phase copper-chloride clusters as well as chloride/water and copper-chloride/water clusters sampled from molecular dynamics (MD) simulations. The parameters were optimized by iteratively training them against configurations generated from ReaxFF MD simulations that are performed multiple times with improved sets of parameters. This cycle was repeated until the ReaxFF results were in accordance with the DFT-derived values. We have performed MD simulations on chloride/water and copper-chloride/water systems to validate the optimized force field. The structural properties of the chloride/water system are in accord with previous experimental and computational studies. The properties of copper-chloride/water agreed with the experimental observations including evidence of the Jahn-Teller distortion. The results of this study demonstrate the applicability of ReaxFF for the precise characterization of aqueous copper chloride. This force field provides a base for the design of a computationally inexpensive tool for the investigation of various properties and functions of metal ions in industrial, environmental, and biological environments.
铜离子在许多酶促和水相过程中发挥着关键作用。对铜配合物基本性质的批判性分析对于理解它们对广泛的化学相互作用的影响至关重要。然而，铜配合物的研究受到强极化和电荷转移效应、多种氧化态以及 Jahn-Teller 畸变等量子效应的影响，这使得实验观察结果难以解释。为了提供一种计算成本低廉但可靠的方法来模拟水相铜化学，已经开发了 ReaxFF 反应力场参数。该力场参数是针对一系列由 DFT 衍生的凝聚相铜-氯化物团簇的能量进行训练的，同时还针对从分子动力学 (MD) 模拟中采样的氯化物/水和铜-氯化物/水团簇进行了训练。通过使用改进的参数多次执行 ReaxFF MD 模拟并针对从这些模拟中生成的构型进行迭代训练，对参数进行了优化。这个循环一直重复，直到 ReaxFF 的结果与 DFT 衍生的值一致。我们已经对氯化物/水和铜-氯化物/水系统进行了 MD 模拟，以验证优化后的力场。氯化物/水系统的结构性质与以前的实验和计算研究一致。铜-氯化物/水的性质与实验观察结果一致，包括 Jahn-Teller 畸变的证据。这项研究的结果表明，ReaxFF 可用于精确表征水相铜氯化物。该力场为设计一种计算成本低廉的工具提供了基础，可用于研究工业、环境和生物环境中金属离子的各种性质和功能。
