Semi-empirical calculation of electronic absorption wavelengths of polyynes, monocyano- and dicyanopolyynes. Predictions for long chain compounds and carbon allotrope carbyne
Résumé
Absorption wavelengths and oscillators strengths have been calculated for the
allowed low-energy electronic transition $^1\Sigma^+ \leftarrow ^1\Sigma^+$
of monocyanopolyynes (HC$_y$N, $y = 1-13$), $^1\Sigma_u^+ \leftarrow
^1\Sigma_g^+$ of polyynes and dicyanopolyynes (HC$_y$H and NC$_y$N, $y =
1-40$). For $y > 18$, the geometries were extrapolated from DFT optimization of
the shortest members. Extrapolation formulas have been drawn up for longer
chains, the asymptotic values of those yield an estimation of the absorption
wavelength (ca. 400 nm) of the hypothetical carbon allotrope carbyne.
Domaines
Chimie théorique et/ou physique
Origine : Fichiers produits par l'(les) auteur(s)