Size dependence of electronic excitation energy in linear C2nH and C2n-1N
- 化学化工－已发表论文 
The geometries, bondings, and vibrational frequencies of C2nH (n=3-9) and C2n-1N(n=3-9) were investigated by means of density functional theory (DFT). The vertical excitation energies for the (XII)-I-2-->(II)-I-2 transitions of C2nH(n=3-9) and for the X(2)Sigma-->(II)-I-2 and the (XII)-I-2-->(II)-I-2 transitions of C2n-1N(n=3-9) have been calculated by the time-dependent density functional theory (TD-DFT) approach. On the basis of present calculations, the explicit expression for the wavelengths of the excitation energies in linear carbon chains is suggested, namely, lambda(0) = [1240. 6A/(2 + root3n+6 - root3n+3)] (1 - Be-Cn), where A = 3.24463, B = 0.90742, and C = 0.07862 for C2nH, and A = 2.94714, B = 0.83929, and C=0.08539, for C2n-1N. In consideration of a comparison of the theory with the experiment, both the expressions are modified as lambda(1) = 0. 92 (lambda(0) +100) and lambda(1) = 0. 95(lambda(0)+90) for C2nH and C2n-1N, respectively.