Optical sum rule anomalies in the cuprates: Interplay between strong correlation and electronic band structure

We theoretically analyze some of the anomalies of the optical sum rules in the high-temperature superconductors. In particular, we address the particularly strong dependence on temperature of the sum rule in the normal state. Both electron-electron correlations and the presence of a Van Hove singularity have been shown to enhance such a dependence. Here, we consider both effects simultaneously by means of dynamical mean-field theory for a two-dimensional Hubbard model with realistic parameters for different cuprates, and we find that the two effects are not cooperative, as they appear to compete with one another in the region of parameters relevant for the experiments. RI Capone, Massimo/A-7762-2008