正交与非正交定域分子轨道的定域性评估

Assessment of the Localization Quality:Orthogonal Versus Non-Orthogonal Localized Molecular Orbitals

摘要: 本文总结了正则分子轨道（CMO），正交定域分子轨道（OLMO）及非正交定域分子轨道（NOLMO）相应的理论，并引入轨道延展度来衡量每种方法生成的分子轨道的定域性能差异，每种方法相对于传统的正则分子轨道轨道其延展度得到提高的比例。通过计算和分析一些典型分子体系的轨道延展度，我们发现，对于占据轨道而言，NOLMO的定域性要比OLMO（通过Boys，Edmiston-Ruedenberg，和Pipek-Mezey方法得到）的定域性都要好，这也与之前已经发表的非正交定域分子轨道的定域性比正交定域分子轨道好10-28%的理论相符。

Abstract: Formulas of canonical molecular orbitals (CMO), orthogonal localized molecular orbital (OLMO), and non-orthogonal localized molecular orbital (NOLMO) to generate molecular orbitals are given. We have compared the orbital spread functions of some testing systems and their reduced percentage compared to the canonical molecular orbitals to assess the localization quality of each method. It is found that for the occupied orbitals, NOLMO is much more localized than CMOs and any OLMOs generated by Boys, Edmiston-Ruedenberg (ER), and Pipek-Mezey (PM) method, up to about 10-28% if the same cutoff threshold is applied.