环状多烯的电子相关。大环近似耦合对理论的性质
Electronic correlation in cyclic polyenes. Behavior of approximate coupled-pair theories for large rings
摘要：
本文用近似耦合对理论（ACP，ACPQ）研究了由Pariser-Parr-Pople（PPP）模型描述的环状多烯（轮烯）C_{M} H_{M}。对于PPP共振积分β =2.5 eV的光谱值的系统，ACP方法在M >= 446时失效，而ACPQ方法在M>194时失效。在ACPQ方法中，当M>170时，观察到两个接近的解，当M >= 198时，它们变成准简并解。结果表明，ACP和ACPQ方法不能应用于一维金属壳体。
英文摘要：
We investigate the cyclic polyenes (annulenes) C_{M}H_{M}, described by the Pariser--Parr--Pople (PPP) model, by means of the approximate coupled-pair theories (ACP, ACPQ). For the systems with the spectroscopic value of the PPP resonance integral beta=2.5 eV, the ACP method breaks down for M >= 446, and the ACPQ method--for M>194. In the ACPQ method, for M>170, two close lying solutions have been observed that become quasi-degenerate for M >= 198. The results indicate that the ACP and ACPQ methods cannot be applied to the one-dimensional metallic case.
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