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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >A Linearly Scaling QM/MM Method to Study Molecular Crystals Using BRABO/CHARMM: Application to 2-(2-Methyl-3-chloroanilino) Nicotinic Acid
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A Linearly Scaling QM/MM Method to Study Molecular Crystals Using BRABO/CHARMM: Application to 2-(2-Methyl-3-chloroanilino) Nicotinic Acid

机译：使用BRABO / CHARMM的线性缩放QM / MM方法研究分子晶体：在2-（2-甲基-3-氯苯胺基）烟酸中的应用

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摘要

Molecular crystals have been studied using two new forms of the cluster approach: an extended point charge (PCX) and an extended supermolecule (SMX) model. These models extend, using a hybrid quantum mechanical/molecular mechanical (QM/MM) approach, that part of the molecular environment that was previously described by point charges in, respectively, the point charge (PC) and supermolecule (SM) models. After interfacing the ab initio program BRABO with the molecular mechanics program CHARMM, the PCX and SMX models have been tested on formamide oxime, α-glycine, and the yellow form of dimethyl 3,6-dichloro-2,5-dihydroxyterephthalate. PCX results are in notably better agreement with experimental results than PC results and are shown to be a viable alternative to SM calculations. For α-glycine, the SMX model improves results over the SM model. For dimethyl 3,6-dichloro-2,5-dihydroxyterephthalate, it was shown that the SMX model can give SM-quality results when fewer neighbors are included in the wave function, thereby reducing the computation time significantly. As a second part of this study, the PCX model was applied to the geometry optimization of the four polymorphs of 2-(2-methyl-3-chloroanilino) nicotinic acid. In contrast to a previous study using the PC model, the newly developed PCX model introduced in this study allowed full geometry optimization of all polymorphs.
机译：已经使用两种新形式的簇方法研究了分子晶体：扩展点电荷（PCX）和扩展超分子（SMX）模型。这些模型使用混合量子力学/分子力学（QM / MM）方法扩展了分子环境中先前由点电荷（PC）和超分子（SM）模型分别描述的部分分子环境。在从头算程序BRABO与分子力学程序CHARMM连接后，已经在甲酰胺肟，α-甘氨酸和黄色形式的3,6-二氯-2,5-二羟基对苯二甲酸二甲酯上测试了PCX和SMX模型。与PC结果相比，PCX结果与实验结果的一致性更好，并且被证明是SM计算的可行替代方案。对于α-甘氨酸，SMX模型优于SM模型。对于3,6-二氯-2,5-二羟基对苯二甲酸二甲酯，研究表明，当波动函数中包含的邻域更少时，SMX模型可以给出SM质量的结果，从而大大减少了计算时间。作为本研究的第二部分，将PCX模型应用于2-（2-甲基-3-氯苯胺基）烟酸的四个多晶型物的几何优化。与以前使用PC模型进行的研究相比，本研究中引入的新开发的PCX模型可以对所有多晶型物进行完整的几何优化。

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