Models of excitations in CuGeO3

The excitations of CuGeO3 are discussed using a model in which pairs of Cu spins are in a spin-singlet state and excitations are made to the excited triplet states. Unless the exchange constants are known independently, the dispersion curves cannot be distinguished experimentally from those of conventional spin waves. The models and conventional spin-wave theory give very different values for the exchange constants which are calculated. Extensions of the calculations to include multi-excitation processes and other systems are suggested.