Excitonic cluster model of strongly correlated electronic systems

An excitonic cluster model is proposed to describe the optical responses of strongly correlated electronic systems, e.g. antiferromagnetic insulators of parent crystals of high-temperature superconductors. This model can take into account both the strong correlation effect of 3d-electrons and the itinerant nature of electronic excitations. Consequently both the electron-hole bound and unbound states can be described on the same footing. As a result, we can resolve the mystery of resonance enhancement of 2-magnon Raman scattering, and remove inconsistencies in the understanding of the absorption spectrum, the photoconductivity spectrum, and large-shift Raman signals.