Dračínský Martin, Bouř Petr, Hodgkinson Paul
Institute of Organic Chemistry and Biochemistry , Flemingovo nám. 2, 16610 Prague, Czech Republic.
Department of Chemistry, Durham University , South Road, DH1 3LE Durham, United Kingdom.
J Chem Theory Comput. 2016 Mar 8;12(3):968-73. doi: 10.1021/acs.jctc.5b01131. Epub 2016 Feb 22.
The influence of temperature on NMR chemical shifts and quadrupolar couplings in model molecular organic solids is explored using path integral molecular dynamics (PIMD) and density functional theory (DFT) calculations of shielding and electric field gradient (EFG) tensors. An approach based on convoluting calculated shielding or EFG tensor components with probability distributions of selected bond distances and valence angles obtained from DFT-PIMD simulations at several temperatures is used to calculate the temperature effects. The probability distributions obtained from the quantum PIMD simulations, which includes nuclear quantum effects, are significantly broader and less temperature dependent than those obtained with conventional DFT molecular dynamics or with 1D scans through the potential energy surface. Predicted NMR observables for the model systems were in excellent agreement with experimental data.
利用路径积分分子动力学（PIMD）以及屏蔽和电场梯度（EFG）张量的密度泛函理论（DFT）计算，探究了温度对模型分子有机固体中核磁共振化学位移和四极耦合的影响。一种基于将计算得到的屏蔽或EFG张量分量与在几个温度下从DFT-PIMD模拟获得的选定键距和价角的概率分布进行卷积的方法，被用于计算温度效应。从包含核量子效应的量子PIMD模拟获得的概率分布，比通过传统DFT分子动力学或通过势能面的一维扫描获得的概率分布显著更宽且对温度的依赖性更小。模型系统预测的核磁共振可观测量与实验数据高度吻合。
