Reactive Molecular Dynamics at Constant Pressure via Nonreactive Force Fields: Extending the Empirical Valence Bond Method to the Isothermal-Isobaric Ensemble.
Reactive Molecular Dynamics at Constant Pressure via Nonreactive Force Fields: Extending the Empirical Valence Bond Method to the Isothermal-Isobaric Ensemble.
复制标题
通过非反应力场进行恒压反应分子动力学：将经验价键方法扩展到等温等压系综。
DOI：
10.1021/acs.jpca.0c05461
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发表时间：
2020
期刊：
影响因子：
--
通讯作者：
Scivetti I
中科院分区：
文献类型：
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作者：
Scivetti I
经验价键（EVB）方法提供了一个合适的框架，以获得反应势通过耦合的非反应力场。在这种形式主义中，大多数实现的耦合项都是使用依赖于空间坐标的函数形式构建的，而参数则与参考数据拟合，以模拟参与非反应状态之间的化学变化。在这项工作中，我们表明，使用这样的耦合项排除了凝聚相系统的应力张量的计算，并防止在等温等压（NPT）合奏进行EVB分子动力学的可能性。或者，我们利用耦合项依赖于能隙，定义为参与非反应力场之间的能量差，并推导出适合计算的EVB应力张量的一般表达式。实施这种新的方法进行测试的一个单一的反应性的丙二醛在非反应性的水溶剂化的模型。质量密度和概率分布的值的能隙计算的NPT合奏揭示了一个可以忽略不计的作用的反应电位在低浓度的解决方案的限制，从而证实了第一次的有效性的近似的基础上的规范NVT合奏，习惯采用EVB模拟。所提出的形式主义也旨在有助于未来的EVB方法的实现和扩展，以研究高浓度溶液的极限。
The Empirical Valence Bond (EVB) method offers a suitable framework to obtain reactive potentials through the coupling of nonreactive force fields. In this formalism, most of the implemented coupling terms are built using functional forms that depend on spatial coordinates, while parameters are fitted against reference data to model the change of chemistry between the participating nonreactive states. In this work, we demonstrate that the use of such coupling terms precludes the computation of the stress tensor for condensed phase systems and prevents the possibility to carry out EVB molecular dynamics in the isothermal-isobaric (NPT) ensemble. Alternatively, we make use of coupling terms that depend on the energy gaps, defined as the energy differences between the participating nonreactive force fields, and derive a general expression for the EVB stress tensor suitable for computation. Implementation of this new methodology is tested for a model of a single reactive malonaldehyde solvated in nonreactive water. Mass densities and probability distributions for the values of the energy gaps computed in the NPT ensemble reveal a negligible role of the reactive potential in the limit of low concentrated solutions, thus corroborating for the first time the validity of approximations based on the canonical NVT ensemble, customarily adopted for EVB simulations. The presented formalism also aims to contribute to future implementations and extensions of the EVB method to research the limit of highly concentrated solutions.