Use of the CNDO Method in Spectroscopy. I. Benzene, Pyridine, and the Diazines
Use of the CNDO Method in Spectroscopy. I. Benzene, Pyridine, and the Diazines
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CNDO 方法在光谱学中的应用。
DOI：
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发表时间：
1968
期刊：
影响因子：
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通讯作者：
H. Jaffe
中科院分区：
文献类型：
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作者：
J. D. Bene;H. Jaffe
CNDO 方法已通过替换与 Pariser-Parr-Pople 方法中使用的类似的半经验库仑积分进行了修改，并引入了新的经验参数 κ 来区分 σ 轨道之间的共振积分和 π 轨道之间的共振积分。参数化变化的CNDO方法被扩展到电子谱的计算，并应用于等电子化合物苯、吡啶、哒嗪、嘧啶和吡嗪。获得的结果通过有限的 CI 计算进行了细化，并与最佳可用实验数据进行了比较。研究发现，n→π* 和 π→π* 单线态-单线态跃迁的一致性非常令人满意。比较了吡啶和二嗪中 pi 和孤对轨道的相对能量，并对观察到的级数提出了解释。此外，还讨论了这些化合物中“孤对电子”的性质。
The CNDO method has been modified by substitution of semiempirical Coulomb integrals similar to those used in the Pariser‐Parr‐Pople method, and by the introduction of a new empirical parameter κ to differentiate resonance integrals between σ orbitals from those between π orbitals. The CNDO method with this change in parameterization is extended to the calculation of electronic spectra and applied to the isoelectronic compounds benzene, pyridine, pyridazine, pyrimidine, and pyrazine. The results obtained were refined by a limited CI calculation and compared with the best available experimental data. It was found that the agreement was quite satisfactory for both n→π* and π→π* singlet‐singlet transitions. The relative energies of the pi and lone‐pair orbitals in pyridine and the diazines are compared and an explanation proposed for the observed orders. Also, the nature of the “lone pairs” in these compounds is discussed.