The static response and the local-field factor of the 2-D electron fluid

The static local-field factor (LFF) of the interacting 2-D fluid is calculated nonperturbatively using a mapping of the quantum fluid to a classical Coulomb fluid [Phys. Rev. Let., {\bf 87}, 206 (2002)]. The LFF for the paramagnetic fluid DIFFERS MARKEDLY from expectations from standard perturbation theory. Our result for the LFF has a maximum close to 3$k_F$, while perturbation methods yield a maximum near 2$k_F$. The available quantum Monte Carlo data seem to agree with our results.These findings imply that many effects, e.g., Friedel oscillations, Kohn anomalies, effective electron-electron interactions, etc., are affected by the strong correlations among anti-parallel spins in 2D.