Dynamic and structural models of pyrimidine in the lowest excited singlet state

Problems on the normal vibrations of pyrimidine in the ground and excited states are solved. The matrices of rotation and shift of normal coordinates due to electronic excitation and Franck-Condon integrals are calculated. The vibronic spectra of pyrimidine are interpreted. Based on this interpretation, bond lengths and bond angles in the electronically excited first singlet state of the molecule are calculated: C₁C₂ 1.388 å, C₂N₃ 1.366 å, N₃C₄ 1.352 å, C-H 1.099 å; C₆C₁C₂ 105.5?, N₃C₄N₅ 127.8?, H₂C₂N₃ 110.1?.