A Dynamical Quantum Cluster Approach to Two-Particle Correlation Functions in the Hubbard Model

Hochkeppel, S.
Assaad, F. F.
Hanke, W.
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We investigate the charge- and spin dynamical structure factors for the 2D one-band Hubbard model in the strong coupling regime within an extension of the Dynamical Cluster Approximation (DCA) to two-particle response functions. The full irreducible two-particle vertex with three momenta and frequencies is approximated by an effective vertex dependent on the momentum and frequency of the spin/charge excitation. In the spirit of the DCA, the effective vertex is calculated with quantum Monte Carlo methods on a finite cluster. On the basis of a comparison with high temperature auxiliary field quantum Monte Carlo data we show that near and beyond optimal doping, our results provide a consistent overall picture of the interplay between charge, spin and single-particle excitations.
Comment: 8 pages, 11 figures
Condensed Matter - Strongly Correlated Electrons