AM1 and DFT study of polarizability of nitrogen-containing octatetraene with donor substituents: Comparative investigation

We report density functional theory (DFT) studies of the dipole polarizabilities of nitrogen-containing octatetraene with a number of Π-electron donor substituent at the end parts. All geometries were optimized at the B3LYP/6-311++G(d,p) level of theory and polarizabilities were done at the same level of theory. The results indicate that for the NO2–(CHCH)4–Y systems we find group polarizabilities in the order: N(Me)2 > NBr2 > OCH3 > Br > NH2 > OH > CH3 > NF2 > H∼F.Semi empirical AM1 and QSAR-quality empirical calculations show poor quantitative agreement with the DFT results, but give excellent statistical correlation coefficients with the DFT values. This implies that the results of such cheaper calculations can suitably scaled for predictive purpose.