Electronic spectra of polyynes HC2nH
- 化学化工－已发表论文 
Density functional theory with the B3LYP functional is used to determine the geometries and vibrational frequencies of HC2nH (n = 1 similar to 13). The X(1)Sigma(g)(+) --> l(1)Sigma(u)(+) vertical transition energies of HC2nH (n = 1 similar to 5) have been 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.