Dahlke Erin E, Truhlar Donald G
J Phys Chem B. 2005 Aug 25;109(33):15677-83. doi: 10.1021/jp052436c.
The accuracy of existing density functional methods for describing the noncovalent interaction energies in small water clusters is investigated by testing 25 density functionals against a data set of 28 water dimers and 8 water trimers whose structures are taken from the literature and from simulations. The most accurate functionals are found to be PW6B95 with a mean unsigned error of 0.13 kcal/mol and MPWB1K and B98 with mean unsigned errors of 0.15 kcal/mol; the best functional with no Hartree-Fock exchange is mPWLYP, which is a GGA with a mean unsigned error of 0.28 kcal/mol. In comparison, the most popular GGA functionals, PBE and BLYP, have mean unsigned errors of 0.52 and 1.03 kcal/mol, respectively. Since GGAs are very cost efficient for both condensed-phase simulations and electronic structure calculations on large systems, we optimized four new GGAs for water. The best of these, PBE1W and MPWLYP1W, have mean unsigned errors of 0.12 and 0.17 kcal/mol, respectively. These new functionals are well suited for use in condensed-phase simulations of water and ice.
通过针对28个水二聚体和8个水三聚体的数据集测试25种密度泛函，研究了现有密度泛函方法描述小水团簇中非共价相互作用能的准确性，这些水二聚体和水三聚体的结构取自文献和模拟。发现最准确的泛函是平均绝对误差为0.13 kcal/mol的PW6B95、平均绝对误差为0.15 kcal/mol的MPWB1K和B98；无哈特里-福克交换的最佳泛函是mPWLYP，它是一种平均绝对误差为0.28 kcal/mol的广义梯度近似（GGA）。相比之下，最常用的GGA泛函PBE和BLYP的平均绝对误差分别为0.52和1.03 kcal/mol。由于GGA对于凝聚相模拟和大型系统的电子结构计算都非常经济高效，我们针对水优化了四种新的GGA。其中最好的PBE1W和MPWLYP1W的平均绝对误差分别为0.12和0.17 kcal/mol。这些新泛函非常适合用于水和冰的凝聚相模拟。
