Year: 2001
Type: article
Abstract: We investigate the static charge response for the Hubbard model. Using the slave-boson method in the saddle-point approximation we calculate the charge susceptibility. We find that the random phase approximation (RPA) works quite well close to half filling, breaking, of course, down close to the Mott transition. Away from half filling RPA is much less reliable: Already for very small values of the Hubbard interaction U, the linear response becomes much more efficient than RPA, eventually leading to overscreening already beyond quite moderate values of U. To understand this behavior we give a simple argument, which implies that the response to an external perturbation at large U should actually be strongly nonlinear. This prediction is confirmed by the results of exact diagonalization.
Author: Erik Koch
Institution: Max Planck Institute for Solid State Research
Language: English
Subfield: Condensed Matter Physics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W2082097166