The generalized Kadanoff-Baym ansatz. Computing nonlinear response properties of finite systems

Abstract

For a minimal Hubbard-type system at different interaction strengths U, we investigate the density-response for an excitation beyond the linear regime using the generalized Kadanoff-Baym ansatz (GKBA) and the second Born (2B) approximation. We find strong correlation features in the response spectra and establish the connection to an involved double excitation process. By comparing approximate and exact Green's function results, we also observe an anomalous U-dependence of the energy of this double excitation in 2B+GKBA. This is in accordance with earlier findings [K. Balzer et al., EPL 98, 67002 (2012)] on double excitations in quantum wells.

PNGF 5

References in corpus (4)

• Many-Body Physics with Ultracold Gases
• Time-dependent second Born calculations for model atoms and molecules in strong laser fields
• Towards a nonequilibrium Green's function description of nuclear reactions: one-dimensional mean-field dynamics
• Electronic double-excitations in quantum wells: solving the two-time Kadanoff-Baym equations

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