Wang Feng
Centre for Molecular Simulation, Swinburne University of Technology, Hawthorn, Melbourne, Victoria 3122, Australia.
J Phys Chem A. 2003 Nov 27;107(47):10199-207. doi: 10.1021/jp0363904.
Fully resolved outer valence orbital momentum distributions (MDs) of n-butane (C4H10) in the ground electronic state (X1Ag) are studied quantum mechanically using RHF/TZVP, density functional theory (DFT) DFT-BP/TZVP, and B3LYP/TZVP methods. The orbital MDs are simulated to reflect the recent experimental conditions with the plane wave impulse approximation (PWIA) and are compared favorably with the available experimental orbital cross sections. However, the majority of the outer valence molecular orbitals (MOs) of n-butane has been only partially resolved experimentally, forming into three clustered MOs of 7ag + 2bg + 6ag, 2au + 6bu and 1bg + 5bu + 5ag. Deconvolution of the clustered MOs is a challenge experimentally but rather straightforward theoretically, as the inversion is a multiple channel process. The outer valence MOs are crucial to understanding the chemical bonding mechanism and the unresolved outer valence orbitals cause significant bonding information loss. This work provides an orbital based assessment to the quality of the RHF/TZVP, DFT-BP/TZVP, and B3LYP/TZVP models using orbital MD information, by decomposing the clustered outer valence MOs of n-butane, which also reveals the bonding mechanism of the species.
利用RHF/TZVP、密度泛函理论（DFT）的DFT - BP/TZVP和B3LYP/TZVP方法，对处于基电子态（X1Ag）的正丁烷（C4H10）的完全解析的外层价轨道动量分布（MDs）进行了量子力学研究。采用平面波脉冲近似（PWIA）对轨道MDs进行模拟，以反映最近的实验条件，并与现有的实验轨道截面进行了良好的比较。然而，正丁烷的大多数外层价分子轨道（MOs）在实验上仅得到部分解析，形成了7ag + 2bg + 6ag、2au + 6bu和1bg + 5bu + 5ag三个聚集的MOs。聚集MOs的去卷积在实验上是一项挑战，但在理论上相当直接，因为反演是一个多通道过程。外层价MOs对于理解化学键合机制至关重要，而未解析的外层价轨道会导致大量键合信息丢失。这项工作通过分解正丁烷的聚集外层价MOs，利用轨道MD信息对RHF/TZVP、DFT - BP/TZVP和B3LYP/TZVP模型的质量进行了基于轨道的评估，这也揭示了该物种的键合机制。
