Shape and localization of soliton waves in the triplet excited state of polymethine dyes

A quantum-chemical study was carried out on the shape and localization of solitons in polymethine dyes in the triplet excited state. The transition of ions of polymethine dyes to this state was shown to give rise to two-component electron density waves of opposite spin being in the opposite phase and, as a result, waves of alternating spin density appear as well as bond length waves with three minima. Two of these minima are linked to separate components of electron density soliton waves, while the third minimum localized in the center of the conjugation chain corresponds to a soliton wave of the total charge. It was established that the soliton waves are asymmetric due to a different number of electrons with spin and spin , especially in ions with a short chain. The introduction of terminal groups enhances the asymmetry and this effect depends significantly on the type of terminal group.