We compute the one-particle spectral function and the optical conductivity for the two-dimensional Hubbard model on a square lattice. The computational method is cellular dynamical mean-field theory in which a four-site Hubbard plaquette is embedded in a self-consistent bath. We obtain a "kink" feature in the dispersion of the spectral function and a mid-infrared (mid-IR) absorption peak in the optical conductivity, consistent with experimental data. Of the 256 plaquette states, only a single state which has d x2 - y2 symmetry contributes to the mid-IR, thereby suggesting a direct link with the pseudogap. Local correlations between doubly and singly occupied sites which lower the kinetic energy of a hole are the efficient cause of this effect.
|Original language||English (US)|
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|State||Published - Dec 1 2008|
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics