用分子片轨道逐步剔除法研究电子离域  

A Theoretical Study of Electronic Delocalization with Progressive Orbital Deletion Procedure

作　　者：丁涪江[1] 

机构地区：[1]四川师范大学化学系 成都610066

出　　处：《化学学报》2002年第4期612-616,共5页Acta Chimica Sinica

摘　　要：估计分子中不同类型的电子离域作用 (如p π→d π和p π→σ )的相对强弱对理解分子中化学键的本质有关键的作用 .剔除某一分子片轨道 (如d π或σ )后分子体系能量的改变可用来计算电子离域到该轨道的离域能 .由于轨道之间的相互作用 ,使离域能的计算与轨道剔除的次序有关 .为克服这种不确定性 ,可以逐步轮流增加某一对特定轨道 (d π和σ )的库仑积分 ,以使这对轨道在分子波函数中的比重逐步减少 ,即将这对轨道轮流逐步剔除 .这样可将轨道间的相互影响减小以至消除 ,从而得到各轨道的精确的离域能 .以H3 PO中P—O键为例说明了轨道逐步剔除方法的应用 .It is very useful for understanding the chemical bonds in molecules to evaluate the electronic delocalization energy between different orbitals ( for example, p-pi --> d-pi and p-pi --> sigma*). The electronic delocalization energy could be obtained by performing HF-SCF calculations with and without some designated orbitals. Because of the interaction of orbitals the calculated delocalization energy is different if the order in which the orbitals are deleted is different. A progressive orbital deletion procedure is proposed to overcome this difficulty. The dominant characteristic of the procedure is that the Coulomb integral of a chosen orbital is shifted progressively by a one-electron operator. While the Coulomb integral increases step by step, the relevant orbital is deleted from the molecular wavefunction step by step. In this way, the interaction between orbitals is decreased and the accurate delocalization energy can be obtained. The molecule of H3PO is discussed as an example.

关 键 词：分子片轨道逐步剔除法 电子离域 化学键 从头算 离域能 量子化学 分子轨道 

分 类 号：O641[理学—物理化学]