Unravelling the nonlinear ideal density response of manybody systems
Abstract
Nonlinear density response theory is revisited focusing on the harmonically perturbed finite temperature uniform electron gas. Within the noninteracting limit, brute force quantum kinetic theory calculations for the quadratic, cubic, quartic and quintic responses reveal a deep connection with the linear response. Careful analysis of the static long wavelength limit led us to conjecture a canonical noninteracting form that expresses arbitrary order nonlinear responses as the weighted sum of the linear responses evaluated at all multiple harmonics. This harmonic expansion is successfully validated against ab initio path integral Monte Carlo simulations.
 Publication:

EPL (Europhysics Letters)
 Pub Date:
 May 2023
 DOI:
 10.1209/02955075/acd3a6
 arXiv:
 arXiv:2303.09223
 Bibcode:
 2023EL....14244001T
 Keywords:

 Condensed Matter  Quantum Gases;
 Condensed Matter  Statistical Mechanics;
 Physics  Plasma Physics
 EPrint:
 7 pages, 3 figures, 169 pages of supplementary material