Determination of an effective one-electron spectrum from the plasmon dispersion of nearly optimally doped Bi2Sr2CaCu2O8

An effective electronic one-particle spectrum of the CuO2 planes in nearly optimally doped Bi2Sr2GaCu2O8 is determined by a method analyzing plasmon dispersion data obtained in electron energy-loss experiments in the normal state. The resulting effective spectrum yields a Fermi surface with the correct topology and which is in remarkable quantitative agreement with that obtained in recent photoemission experiments. In spite of its simplicity the effective model spectrum agrees well with the noninteracting parts of the antibonding Cu-O band as obtained in band-structure calculations based on the local-density approximation. The results indicate that in contrast to other experiments in such systems strong correlation effects are of minor importance for the: plasmon dispersion. Additionally, the method yields also the background dielectric constant. The proposed method is applicable to other low-dimensional systems. [S0163-1829(99)11625-4].