Central peak in polaronic crystals

A possibility of the central peak appearance in crystals with low concentration of small-radius polarons is pointed out. The intensity of the central peak increases sharply with the softening of the phonon mode $\text{(ω}{}_{\mathrm{<mtext>K</mtext><mtext>0</mtext>}}\text{→ 0)}$ in the vicinity of the structural phase transition . The peak width γ₀ is determined by the probability W of the polaron hopping between the sites γ₀ = K₀²a²W.