Department of Chemistry, New York University, New York, New York 10003, USA.
J Chem Phys. 2012 Jul 28;137(4):044506. doi: 10.1063/1.4736712.
It is generally believed that studies of liquid water using the generalized gradient approximation to density functional theory require dispersion corrections in order to obtain reasonably accurate structural and dynamical properties. Here, we report on an ab initio molecular dynamics study of water in the isothermal-isobaric ensemble using a converged discrete variable representation basis set and an empirical dispersion correction due to Grimme [J. Comp. Chem. 27, 1787 (2006)]. At 300 K and an applied pressure of 1 bar, the density obtained without dispersion corrections is approximately 0.92 g/cm(3) while that obtained with dispersion corrections is 1.07 g/cm(3), indicating that the empirical dispersion correction overestimates the density by almost as much as it is underestimated without the correction for this converged basis. Radial distribution functions exhibit a loss of structure in the second solvation shell. Comparison of our results with other studies using the same empirical correction suggests the cause of the discrepancy: the Grimme dispersion correction is parameterized for use with a particular basis set; this parameterization is sensitive to this choice and, therefore, is not transferable to other basis sets.
人们普遍认为，使用密度泛函理论的广义梯度近似来研究液态水需要色散校正，才能获得合理准确的结构和动力学性质。在这里，我们报告了使用收敛离散变量表示基组和 Grimme [J. Comp. Chem. 27, 1787 (2006)] 提出的经验色散校正，在等温和等压条件下进行的分子动力学研究。在 300 K 和 1 巴的应用压力下，没有色散校正的密度约为 0.92 g/cm(3)，而有色散校正的密度为 1.07 g/cm(3)，这表明经验色散校正对密度的高估程度几乎与没有校正时的低估程度一样大。对于这个收敛基组，这种经验色散校正的参数化是针对特定基组的；这种参数化对这个选择很敏感，因此不能转移到其他基组。径向分布函数在第二溶剂化壳层中表现出结构的损失。我们的结果与使用相同经验校正的其他研究的比较表明了这种差异的原因：Grimme 色散校正适用于特定的基组；
