聚炔烃电子吸收光谱的理论研究

Electronic Spectra of Polyynes HC_(2n)H

应用DFT/B3LYP方法,在6-31G水平上计算了HC2nH(n=1～13)的基态平衡几何构型和振动频率.在基态平衡构型下,通过TD-B3LYP/cc-PVTZ计算,确定了HC2nH(n=1～5)体系X1Σ+g11Σ+u电子跃迁的能量和对应的振子强度.根据计算结果并结合先前的价键研究导出了HC2nH聚炔烃体系X1Σ+g11Σ+u电子跃迁能与体系大小n有关的解析表达式.

Density functional theory with the B3LYP functional is used to determine the geometries and vibrational frequencies of HC 2nH (n=1～13). The vertical transition energies of HC 2nH (n=1～5) havebeen estimated by TD B3LYP/cc PVTZ calculations.On the basis of theoretical calculations,a generally analytic expression for the chain size n dependence of the vertical transition energy was suggested,which can predict excellent excitation energies in comparison with available observed bands.Current calculations reveal that a nonlinear behavior for the even numbered HC2nH between the excitation energy and the number of carbon atoms.