Exploring Reaction Energy Profiles Using the Molecules-in-Molecules Fragmentation-Based Approach
Exploring Reaction Energy Profiles Using the Molecules-in-Molecules Fragmentation-Based Approach
复制标题
使用基于分子碎片的方法探索反应能量分布
DOI：
10.1021/acs.jctc.9b00152
复制
发表时间：
2019
影响因子：
5.5
通讯作者：
Raghavachari, Krishnan
中科院分区：
文献类型：
--
作者：
Gupta, Ankur Kumar;Thapa, Bishnu;Raghavachari, Krishnan
分子中分子（MIM）的碎片为基础的方法已成功地用于在以前的研究中获得的能量，优化的几何形状，和大分子系统的光谱性质。目前的工作描绘了一个协议，使用MIM方法研究多步化学反应的势能分布。在复杂的多步化学反应中，当反应物质过渡到新的反应步骤时，需要改变碎裂方案，从而导致反应势能曲线的不连续性。在我们的方法中，反应中特定步骤的碎裂方案是根据与该步骤相关的键合变化的性质来选择的。因此，反应物、过渡态和产物在整个反应步骤中被一致地处理，从而导致该步骤的准确能垒。在描述两个反应步骤之间的过渡点处的反应中间体的能量时，现在出现了不连续性，这两个反应步骤由两种不同的碎裂方案处理。为了解决这个问题，我们提出了一个系统的程序来获得连续的势能曲线，从它们的初始位置移动最少。修正后的MIM势能曲线是连续的，活化能保持不变。按照这种方法，涉及大分子物种的复杂反应的能量分布可以在高水平的理论与合理的计算成本。
The Molecules-in-Molecules (MIM) fragmentation-based approach has been successfully used in previous studies to obtain the energies, optimized geometries, and spectroscopic properties of large molecular systems. The present work delineates a protocol to study the potential energy profiles for multistep chemical reactions using the MIM methodology. In a complex multistep chemical reaction, the fragmentation scheme needs to be changed as the reacting species transition into a new reaction step, resulting in a discontinuity in the potential energy curve of the reaction. In our approach, the fragmentation scheme for a particular step in a reaction is chosen on the basis of the nature of the bonding changes associated with that step. Thus, the reactant, transition state, and product are treated consistently throughout the reaction step, leading to an accurate energy barrier for that step. The discontinuity now occurs in describing the energies of reaction intermediates at the transition point between two reaction steps that are treated by two different fragmentation schemes. To address this issue, we propose a systematic procedure for obtaining continuous potential energy curves that are least shifted from their initial positions. The corrected MIM potential energy curves are continuous with activation energies preserved. Following this approach, energy profiles of complex reactions involving large molecular species can be obtained at high levels of theory with a reasonable computational cost.