Mobile valence-alternation domain walls in Wolffram's red salt

A theoretical analysis of the excitation spectrum of the long-chain of Wolffram's red salt is presented. Because of the twofold degeneracy of the ground state of the dimerized chain, elementary excitations corresponding to topological solitons, or propagating domain walls are obtained. Such domain wall motions govern the charge-lattice relaxation process in Wolffram's red salt at low temperatures.