Study of excited states of furan and pyrrole by time-dependent density functional theory

Excited states of furan and pyrrole were studied by time-dependent density functional theory. The effect of basis set and density functional on the vertical excitation energies was investigated. Energy gradients and dipole moments were evaluated analytically. Stationary points on the lowest excited states were determined. Harmonic frequencies and (v′=0←v=0) excitation energies were evaluated. Many of the results agree well with the experimental values available as well as most recent theoretical ab initio values, but there remain discrepancies in the valence states. The dipole moments of many excited states show a large variation with the basis set and functional; this is due to the fact that the states have an extremely large polarisability.