论文标题
中心$σ$ - 孔对卤素分子中以原子为中心的部分电荷的影响
The Effect of Off-Center $σ$-Hole on the Atom-Centered Partial Charges in Halogenated Molecules
论文作者
论文摘要
部分原子电荷属于计算化学的关键概念。但是，在某些情况下，它们无法描述分子的静电。一个这样的例子是$σ$ - 孔，这是位于卤素和其他原子上的正静电电位区域。在分子力学中，$σ$ - 孔通常被建模为伪原子，其正电荷位于卤素核附近。在这里，我们解决了一个问题，伪原子在多大程度上影响分子中其他原子的部分电荷。为此，我们已经彻底分析了由锌数据库中2300多个卤代分子的部分电荷，这些电荷是由受限静电势（RESS）方法计算得出的，并将其与包括伪原子在内的REXP拟合的电荷进行了比较。我们表明，伪原子改善了绝大多数分子的电荷拟合。 $σ$ - 孔被建模为偏心电荷，会影响来自卤素的三个共价键内的原子。
Partial atomic charges belong to key concepts of computational chemistry. In some cases, however, they fail in describing the electrostatics of molecules. One such example is the $σ$-hole, a region of positive electrostatic potential located on halogens and other atoms. In molecular mechanics, the $σ$-hole is often modeled as a pseudo-atom with a positive partial charge located off the halogen nucleus. Here we address a question, to what extent the pseudo-atom affects partial charges of other atoms in the molecule. To this aim, we have thoroughly analyzed partial charges of over 2300 halogenated molecules from the ZINC database calculated by the Restricted Electrostatic Potential (RESP) method and compared them with the charges fitted by RESP including the pseudo-atom. We show that the pseudo-atom improves charge fitting for a vast majority of molecules. The $σ$-hole, modeled as the off-center charge, affects the atoms within three covalent bonds from the halogen.
