SHELL-MODEL PARAMETERS FOR LAYERED COPPER OXIDES

The lattice dynamics of layered copper oxides is usually studied within the shell model using parameters obtained from calculations of simpler oxides. In this paper, this approach is complemented with a model treatment of the cation-oxygen short-range potential parameters. For two groups of ionic pairs, Ae(2+)-O2- and Re3+-O2- (where Ae is an alkaline earth element and Re is a rare earth element or yttrium), the estimated values of these parameters and various cation coordinations are applied in shell model calculations of Ca2CuO3, (Pr, Sr)(2)CuO4 (T, T', and T* phases), YBaCuFeO5, YBa2Fe3O8 and HgBa2CuO4. The results of the calculations are found to be in reasonable agreement with the existing Raman and infrared data.