A possible demonstration of cooperative dynamical Jahn-Teller effect in Raman scattering spectrum of rhombohedral $LaMn{O}_3$

Abstract

The Raman scattering (RS) spectra of rhombohedral $LaMn{O}_3$ is considered. It is shown that broad high intensity RS line at 640 $c{m}^{-1}$ could be explained in the framework of cooperative dynamical Jahn-Teller effect. This hypothesis is illustrated through the lattice dynamics calculations explicitly allowing for the electron-phonon term both in crystal energy and in dynamical matrix. The averaging scheme for the one mode cooperative dynamical effect is proposed