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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Effective Fragment Potential Method for H-Bonding: How To Obtain Parameters for Nonrigid Fragments
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Effective Fragment Potential Method for H-Bonding: How To Obtain Parameters for Nonrigid Fragments

机译：用于H键合的有效片段电位方法：如何获得非碎片的参数

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摘要

Accuracy of the effective fragment potential (EFP) method was explored for describing intermolecular interaction energies in three dimers with strong H-bonded interactions, formic acid, formamide, and formamidine dimers, which are a part of HBC6 database of noncovalent interactions. Monomer geometries in these dimers change signifiCantly as a function of intermonomer separation. Several EFP schemes were considered, in which fragment parameters were prepared for a fragment in its gas-phase geometry or recomputed for each unique fragment geometry. Additionally, a scheme in which gas-phase fragment parameters are shifted according to relaxed fragment geometries is introduced and tested. EFP data are compared" against the coupled cluster with single, double, and perturbative triple excitations (CCSD(T)) method in a complete basis set (CBS) and the symmetry adapted perturbation theory (SAPT). All considered EFP schemes provide a good agreement with CCSD(T)/CBS for binding energies at equilibrium separations, with discrepancies not exceeding 2 kcal/mol. However, only the schemes that utilize relaxed fragment geometries remain qualitatively correct at shorter than equilibrium intermolecular distances. The EFP scheme with shifted parameters behaves quantitatively similar to the scheme in which parameters are recomputed for each monomer geometry and thus is recommended as a computationally efficient approach for large-scale EFP simulations of flexible systems.
机译：探讨了有效片段电位（EFP）方法的准确性，用于描述具有强H键合相互作用，甲酸，甲酰胺和甲酰胺二聚体的三个二聚体中的分子间相互作用能，这是非共价相互作用的HBC6数据库的一部分。这些二聚体中的单体几何形状随着串组合器分离而显着变化。考虑了几种EFP方案，其中为其气相几何形状中的片段制备片段参数，或者为每个独特的片段几何重新计算。另外，引入并测试了一种方案，其中气相片段参数换档并进行测试。以完整的基础集（CBS）和对称性适应的扰动理论（SAPT）将EFP数据与单个，双和扰动三重激发（CCSD（T））方法进行比较“对抗耦合集群。所有考虑的EFP方案都提供了良好的与CCSD（T）/ CBS的达成协议，用于在平衡分离时绑定能量，其差异不超过2千卡/摩尔。但是，只有利用缓和片段几何形状的方案仍然在短于平衡分子间距离短的情况下保持定性校正。具有偏移参数的EFP方案行业类似于针对每个单体几何重新计算参数的方案，因此建议作为柔性系统的大规模EFP模拟的计算有效方法。

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