Self-trapped excitations in the Peierls-Froehlich state

It is shown that the stationary excited states of a one-dimentional Peierls dielectric are amplitude solitons. They are produced by the self-trapping of an electron initially excited across the optical gap 2Δ0. The energy of the soliton is Wsub(s) = (2/π)Δ0, charge esub(s) = 0, spin s = 1/2. The gap parameter has the form Δ(x) = Δ0 th (xΔ0/vsub(F)). The soliton carries a singly occupied v0 = 1 localized state with an energy at the centre of the gap E0 = 0. For a system with a commensurability 1:2 the occupation number may be arbitrary v0 = 0, 1, 2 and the soliton may have a charge esub(s) -e, 0, e. It is proved that the account of interactions between electrons conserves the property esub(s) = 0. A small local charge appears as a result of phonon dispersion. Interaction between chains leads to the levelling out of the phase discontinuity of the function Δ(x) at distances l approximately vsub(F)/Tsub(c) >> vsub(F)/Δ0 (Tsub(c) is the three-dimensional ordering temperature). A charge approximately e is trapped in this region. Coupling between chains or commensurability of an order exceeding two lead to an attraction between solitons with a force approximately vsub(F)/l2 at distances < or approximately l. The solitons show themselves in effects of spin resonance, absorption or luminescence at a frequency Δ0 and broadening of the fundamental absorption edge 2Δ0