Density functional studies of conformational properties of conjugated systems containing heteroatoms

The application of the Density Functional (DFT) method to conformational properties, which are pertinent to the parametrization of potential energy functions for molecular modelling of conjugated molecules, is investigated. Conformational structures and energy differences, vibrational spectra and electrostatic potential derived atomic charges have been determined for some nitrogen- and oxygen-substituted 1,3-butadienes. The molecules studied were 1,3-butadiene, 1,4-diaza-1,3-butadiene, 2,3-diaza-1,3-butadiene, glyoxal and acrolein. The calculations indicate that the DFT method performs well for most of the properties studied. Some of the torsional barriers are overestimated, and some minima are calculated too shallow by the DFT method.