A distance-dependent parameterization of the extended Hubbard model for conjugated and aromatic hydrocarbons derived from stretched ethene.
A distance-dependent parameterization of the extended Hubbard model for conjugated and aromatic hydrocarbons derived from stretched ethene.
复制标题
来自拉伸乙烯的共轭和芳香烃的扩展哈伯德模型的距离相关参数化。
作者：
T. Schmalz;L. Serrano;Vicenta Saurí;M. Merchán;J. Oliva
Hubbard模型在物理学中被广泛使用，但大多数化学家都不熟悉，它为化学提供了一个有吸引力的简单模型，超越了自洽场分子轨道近似。当两个电子占据相同的原子轨道时，哈伯德模型向熟悉的休克尔汉密尔顿函数添加了有效的电子-电子排斥力。因此，它打破了激发单重态和三重态之间的简并性，并允许明确的电子相关治疗。我们展示了如何评估的参数模型从高层次的从头计算两个原子片段，然后转移到大分子和聚合物的参数，准确的从头计算是困难或不可能的。最近开发的MS-RASPT 2方法是用来生成准确的势能曲线乙烯作为碳-碳键长的函数，这是用来参数化共轭烃的模型。几个共轭/芳香族分子的测试应用表明，即使该模型是非常简单的，它是能够合理准确的预测键长，并预测分子的激发能在合理的协议从MS-RASPT 2方法。
The Hubbard model, which is widely used in physics but is mostly unfamiliar to chemists, provides an attractive yet simple model for chemistry beyond the self consistent field molecular orbital approximation. The Hubbard model adds an effective electron-electron repulsion when two electrons occupy the same atomic orbital to the familiar Hückel Hamiltonian. Thus it breaks the degeneracy between excited singlet and triplet states and allows an explicit treatment of electron correlation. We show how to evaluate the parameters of the model from high-level ab initio calculations on two-atom fragments and then to transfer the parameters to large molecules and polymers where accurate ab initio calculations are difficult or impossible. The recently developed MS-RASPT2 method is used to generate accurate potential energy curves for ethene as a function of carbon-carbon bond length, which are used to parameterize the model for conjugated hydrocarbons. Test applications to several conjugated/aromatic molecules show that even though the model is very simple, it is capable of reasonably accurate predictions for bond lengths, and predicts molecular excitation energies in reasonable agreement with those from the MS-RASPT2 method.