Dimerisation and charge ordering in linear chain organic conductors

We present an exactly soluble model hamiltonian which describes the competition between the dimerised, and a distinct charge ordered ground state, due respectively to the interaction of the electrons with the acoustic phonons and with the intramolecular vibrations. We show the occurrence of a new phase involving internal distortion as well as displacement of the molecules. Low temperature reduction of the vibrational frequencies are shown to be a direct measure of the coupling strengths involved. © 1974.