Correlated states in finite polyenes: Exact PPP results
Correlated states in finite polyenes: Exact PPP results
复制标题
有限多烯中的相关态：精确的 PPP 结果
DOI：
10.1063/1.443484
复制
发表时间：
1982
影响因子：
4.4
通讯作者：
Z. Soos
中科院分区：
文献类型：
--
作者：
I. Ducasse;T. E. Miller;Z. Soos
价键(VB)图为每个位置有一个价态的系统中的关联态提供了一个方便的基础。给出了包括所有构型相互作用的准确的Pariser-Parr-Pople(PPP)解，适用于八碳四烯(OT)、一种菁染料和各种环状体系。我们展示了用计算机快速生成对称性适应的VB基函数，电子转移引起的变换系数，以及任意选择的与自旋无关的格点间相互作用的稀疏矩阵的迭代解。对于标准的OHNO参数，OT的2 1AG状态被正确放置。将相关态的π电子键级数和电荷与休克尔解和近似解进行了对比。对于N=8位的偶数链和环，发现了强1 1AG→1 1BU转变的长度依赖关系。外推为N-−1时，极限能隙约为3 eV，比聚乙炔的最大吸收值高出约1 eV，聚乙炔是一种名义上的无限多烯。相关性在狭义的.
Valence bond (VB) diagrams provide a convenient basis for correlated states in systems with one valence state per site. The exact Pariser–Parr–Pople (PPP) solution, including all configuration interactions, is presented for octatetraene (OT), a cyanine dye, and various cyclic systems. We demonstrate rapid computer generation of symmetry adapted VB basis functions, of transformation coefficients due to electron transfer, and of iterative solutions of sparse matrices for any choice of spin‐independent intersite interactions. The 2 1Ag state of OT is correctly placed for standard Ohno parameters. The π‐electron bond orders and charges of correlated states are contrasted to Huckel and approximate PPP solutions. The length dependence of the strong 1 1Ag→1 1Bu transition is found for even chains and rings of up to N = 8 sites. Extrapolations as N−1 yield a limiting PPP gap around 3 eV, or about 1 eV above the absorption maximum in polyacetylene, the nominally infinite polyene. The role of correlations in narrow...