Phonon assistance in tunneling for nonideal lattice dynamics.

Abstract

It is shown that in systems such as KCl:${\mathrm{OH}}^{\mathrm{\ensuremath{-}}}$, where the eigenamplitudes of the lattice modes strongly deviate from the ideal behavior near the tunneling center, the coupling strength is enhanced in the high-frequency region and subdued in the low-frequency one. This initiates a decrease of the tunneling rate by more than 1 order of magnitude. Our result provides an explanation for the measured relation between the tunneling rates of KCl:${\mathrm{OH}}^{\mathrm{\ensuremath{-}}}$ and RbBr:${\mathrm{OH}}^{\mathrm{\ensuremath{-}}}$.