标量相对论效应对卤素键和$σ$空穴性质的影响
Assessment of Scalar Relativistic Effects on Halogen Bonding and $σ$-Hole Properties
摘要：
卤素键（X-键）是卤素原子与电子给体之间的非共价相互作用。它经常被合理化的一个区域的正静电势的卤素原子，所谓的$σ$ -孔。X-键的强度随着所涉及的卤素的原子序数而增加，因此对于较重的卤素，相对论效应变得令人担忧。这对X-键合复合物的量子化学描述提出了挑战。为了量化标量相对论效应（SREs）的相互作用能和$σ$ -孔的属性，我们进行了高度精确的耦合簇计算在完整的基组限制的几个X-键合配合物和它们的卤代单体。SRE在幅度上与基组的影响相当。非相对论性计算通常低估了溴化和碘化络合物的吸引力，分别高达5%或23%。与直觉相反，在键临界点的电子密度是更大的SRE自由计算比相对论的。SRE产生更小、更平坦和更正的$σ$ -空穴。最后，我们强调了扩散函数在基组中的重要性，并提供了定量的参数，使用基组与赝势作为一个负担得起的替代更严格的道格拉斯-克罗尔-赫斯相对论理论。
英文摘要：
Halogen bond (X-bond) is a noncovalent interaction between a halogen atom and an electron donor. It is often rationalized by a region of the positive electrostatic potential on the halogen atom, so-called $σ$-hole. The X-bond strength increases with the atomic number of the halogen involved, thus for heavier halogens, relativistic effects become of concern. This poses a challenge for the quantum chemical description of X-bonded complexes. To quantify scalar relativistic effects (SREs) on the interaction energies and $σ$-hole properties, we have performed highly accurate coupled-cluster calculations at the complete basis set limit of several X-bonded complexes and their halogenated monomers. The SREs turned to be comparable in magnitude to the effect of basis set. The nonrelativistic calculations typically underestimate the attraction by up to 5% or 23% for brominated and iodinated complexes, respectively. Counter-intuitively, the electron densities at the bond critical points are larger for SRE-free calculations than for the relativistic ones. SREs yield smaller, flatter, and more positive $σ$-holes. Finally, we highlight the importance of diffuse functions in the basis sets and provide quantitative arguments for using basis sets with pseudopotentials as an affordable alternative to a more rigorous Douglas-Kroll-Hess relativistic theory.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
