Proton NMR relaxation from molecular dynamics: intramolecular and intermolecular contributions in water and acetonitrile
Proton NMR relaxation from molecular dynamics: intramolecular and intermolecular contributions in water and acetonitrile
复制标题
分子动力学的质子核磁共振弛豫：水和乙腈中分子内和分子间的贡献
DOI：
10.1039/c9cp04976b
复制
发表时间：
2019
影响因子：
3.3
通讯作者：
Autschbach, Jochen
中科院分区：
文献类型：
--
作者：
Philips, Adam;Autschbach, Jochen
基于从头算分子动力学（aiMD），利用来自Kohn-Sham（KS）理论的力以及基于力场（FF）的经典动力学，计算了质子在液态水和纯乙腈中的NMR弛豫速率。分子内和分子间的偶极-偶极的贡献被分离，并获得了几乎与实验定量一致的水。利用KS理论得到的核自旋-转动耦合张量计算了乙腈中自旋-转动（SR）对分子内弛豫速率的贡献。他们的列入提高了总计算的分子内速率的实验的两个因素之内。模拟中相邻乙腈分子之间罕见的短时间碰撞事件的采样不足被假设为分子间贡献误差的主要来源。
NMR relaxation rates for protons in liquid water and neat acetonitrile were computed based on ab initio molecular dynamics (aiMD) with forces from Kohn–Sham (KS) theory as well as force-field (FF) based classical dynamics. Intra- and intermolecular dipole–dipole contributions were separated, and nearly quantitative agreement with experiment was obtained for water. Spin-rotation (SR) contributions to the intramolecular relaxation rate in acetonitrile were computed using nuclear SR coupling tensors obtained from KS theory. Their inclusion improved the total computed intramolecular rate to within a factor of two of experiment. Insufficient sampling of rare short-time collision events between neighboring acetonitrile molecules in the simulations is hypothesized as a major source of error in the intermolecular contributions.