Berryman Victoria E J, Baker Matthew G, Boyd Russell J
Department of Chemistry, Dalhousie University , Halifax, Nova Scotia B3H 4R2, Canada.
J Phys Chem A. 2014 Jun 26;118(25):4565-74. doi: 10.1021/jp502541y. Epub 2014 Jun 17.
Density functional theory is used to study a series of model iron porphyrins in the gas phase. In the first part of this study, three range-separated hybrid density functionals developed by Chai and Head-Gordon were assessed; ωB97, ωB97X, and ωB97XD. The effects of including full Hartree-Fock exchange at long-range and dispersion corrections are reported with respect to the geometries and binding energies of oxygen to the iron porphyrin systems. The functionals all correctly predict the quintet ground state for the deoxy-iron porphyrins, where typically hybrid functionals fail and predict a triplet ground state. Including dispersion in ωB97XD is shown to give the best results for the O2 binding energy and geometrical parameters. The second part of the study employs ωB97XD to study iron porphine systems with different amino acids in the axial position. Geometrical parameters are reported and compared to experimental data, where available. Binding energies of the systems with oxygen are also reported and discussed.
密度泛函理论用于研究气相中的一系列模型铁卟啉。在本研究的第一部分，评估了Chai和Head-Gordon开发的三种范围分离的杂化密度泛函；ωB97、ωB97X和ωB97XD。报告了关于氧与铁卟啉体系的几何结构和结合能，包含长程全哈特里-福克交换和色散校正的影响。这些泛函都正确地预测了脱氧铁卟啉的五重基态，而典型的杂化泛函在此处失效并预测为三重基态。结果表明，在ωB97XD中包含色散对O2结合能和几何参数给出了最佳结果。研究的第二部分采用ωB97XD研究轴向位置具有不同氨基酸的铁卟吩体系。报告了几何参数并与现有实验数据进行比较。还报告并讨论了这些体系与氧的结合能。
