Nuclear magnetic shielding constants of liquid water: insights from hybrid quantum mechanics/molecular mechanics models.
Nuclear magnetic shielding constants of liquid water: insights from hybrid quantum mechanics/molecular mechanics models.
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液态水的核磁屏蔽常数：混合量子力学/分子力学模型的见解。
DOI：
10.1063/1.2424713
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发表时间：
2007
期刊：
影响因子：
--
通讯作者：
K. Ruud
中科院分区：
文献类型：
--
作者：
J. Kongsted;C. B. Nielsen;K. Mikkelsen;O. Christiansen;K. Ruud
我们提出了一种不依赖于量规原点的计算结构极化环境中分子的核磁屏蔽张量的方法。该方法基于密度泛函理论（DFT）或Hartree-Fock波函数与分子力学的结合。该方法的独特之处在于，它包括在精确计算核磁屏蔽常数时需要满足的三个重要性质：(i)该模型包括电子相关效应，（ii）该模型使用包括量规在内的原子轨道来给出量规原点无关的结果，以及（iii）使用离散反应场方法自洽地处理环境的影响。根据分子动力学模拟得到的大量溶质-溶剂构型，作者给出了液态水各向同性核磁屏蔽常数的实例计算，采用了显式或隐式处理溶剂极化的电位。对于（17）O和(1)H各向同性屏蔽常数，最佳预测结果与实验数据相当吻合，即，它们再现了（17）O屏蔽的实验溶剂位移到4ppm以内，(1)H屏蔽的溶剂位移到1ppm以内。
We present a gauge-origin independent method for the calculation of nuclear magnetic shielding tensors of molecules in a structured and polarizable environment. The method is based on a combination of density functional theory (DFT) or Hartree-Fock wave functions with molecular mechanics. The method is unique in the sense that it includes three important properties that need to be fulfilled in accurate calculations of nuclear magnetic shielding constants: (i) the model includes electron correlation effects, (ii) the model uses gauge-including atomic orbitals to give gauge-origin independent results, and (iii) the effect of the environment is treated self-consistently using a discrete reaction-field methodology. The authors present sample calculations of the isotropic nuclear magnetic shielding constants of liquid water based on a large number of solute-solvent configurations derived from molecular dynamics simulations employing potentials which treat solvent polarization either explicitly or implicitly. For both the (17)O and (1)H isotropic shielding constants the best predicted results compare fairly well with the experimental data, i.e., they reproduce the experimental solvent shifts to within 4 ppm for the (17)O shielding and 1 ppm for the (1)H shielding.