Loboda Oleksandr, Ingrosso Francesca, Ruiz-López Manuel F, Szalewicz Krzysztof, Millot Claude
Université de Lorraine, SRSMC UMR 7565, Vandoeuvre-les-Nancy F-54506, France.
Department of Physics and Astronomy, University of Delaware, Newark, Delaware 19716, USA.
J Chem Phys. 2016 Jan 21;144(3):034304. doi: 10.1063/1.4939519.
Geometry-dependent distributed polarizability models have been constructed by fits to ab initio calculations at the coupled cluster level of theory with up to noniterative triple excitations in an augmented triple-zeta quality basis set for the water molecule in the field of a point charge. The investigated models include (i) charge-flow polarizabilities between chemically bonded atoms, (ii) isotropic or anisotropic dipolar polarizabilities on oxygen atom or on all atoms, and (iii) combinations of models (i) and (ii). For each model, the polarizability parameters have been optimized to reproduce the induction energy of a water molecule polarized by a point charge successively occupying a grid of points surrounding the molecule. The quality of the models is ascertained by examining their ability to reproduce these induction energies as well as the molecular dipolar and quadrupolar polarizabilities. The geometry dependence of the distributed polarizability models has been explored by changing bond lengths and HOH angle to generate 125 molecular structures (reduced to 75 symmetry-unique ones). For each considered model, the distributed polarizability components have been fitted as a function of the geometry by a Taylor expansion in monomer coordinate displacements up to the sum of powers equal to 4.
通过在点电荷场中，使用增强型三ζ质量基组，在耦合簇理论水平上进行从头计算，并包含至多非迭代三重激发，对水分子进行拟合，构建了与几何结构相关的分布式极化率模型。研究的模型包括：（i）化学键合原子之间的电荷流极化率；（ii）氧原子或所有原子上的各向同性或各向异性偶极极化率；（iii）模型（i）和（ii）的组合。对于每个模型，极化率参数已进行优化，以再现被点电荷极化的水分子的感应能，该点电荷依次占据围绕分子的点网格。通过检查模型再现这些感应能以及分子偶极和四极极化率的能力来确定模型的质量。通过改变键长和HOH角以生成125个分子结构（简化为75个对称唯一的结构），探索了分布式极化率模型的几何依赖性。对于每个考虑的模型，通过在单体坐标位移上进行泰勒展开，将分布式极化率分量拟合为几何结构的函数，展开式的幂次和等于4。
