Genesis of collective excitations in the conductivity spectra of higher borides RB$_6$ and RB$_{12}$ exhibiting a cooperative structural instability

To describe anomalies in the ac conductivity spectra of higher borides RB$_6$ and RB$_{12}$ with the Jahn–Teller structural instability, a model based on the dipole nature of the effect of collective lattice vibrations on electron transport is proposed. The simulation results are compared with the measured spectra, and the crystallographic parameters are estimated.