Mikkelsen Jonas E S, Jensen Frank
Department of Chemistry, Aarhus University, Langelandsgade 140, DK-8000 Aarhus, Denmark.
J Phys Chem A. 2024 May 23;128(20):4168-4175. doi: 10.1021/acs.jpca.4c01890. Epub 2024 May 14.
The molecular dipole polarizability can be decomposed into components corresponding to the charge flow between atoms and changes in atomic dipole moments. Such decompositions are recognized to depend on how atoms are defined within a molecule, as, for example, by Hirshfeld, iterative Stockholder, or quantum topology partitioning of the electron density. For some of these, however, there are significant differences between the numerical results obtained by analytical response methods and finite field calculations. We show that this difference is due to analytical response methods accounting for (only) the change in electron density by a perturbation, while finite field methods may also include a component corresponding to a perturbation-dependent change in the definition of an atom within a molecule. For some atom-in-molecule definitions, such as the iterative Hirshfeld, iterative Stockholder, and quantum topology methods, the latter effect significantly increases the charge flow component. The decomposition of molecular polarizability into atomic charge flow and induced dipole components thus depends on whether the atom-in-molecule definition is taken to be perturbation-dependent.
分子偶极极化率可分解为与原子间电荷流动以及原子偶极矩变化相对应的分量。人们认识到，这种分解取决于分子内原子的定义方式，例如通过赫希菲尔德（Hirshfeld）、迭代股东（iterative Stockholder）或电子密度的量子拓扑划分。然而，对于其中一些方法，通过解析响应方法和有限场计算获得的数值结果存在显著差异。我们表明，这种差异是由于解析响应方法（仅）通过微扰来考虑电子密度的变化，而有限场方法还可能包括一个与分子内原子定义中依赖于微扰的变化相对应的分量。对于一些分子内原子定义，如迭代赫希菲尔德、迭代股东和量子拓扑方法，后一种效应会显著增加电荷流动分量。因此，将分子极化率分解为原子电荷流动和诱导偶极分量取决于分子内原子定义是否被视为依赖于微扰。
