Fig. 4: Electronic pair alignment model for the spectrum of density fluctuations.
From: Electronic pair alignment and roton feature in the warm dense electron gas
Shown is the dispersion ω(q) [i.e., position of the maximum in S(q, ω)] of the warm dense electron gas at the electronic Fermi temperature for a rs = 4 and b rs = 10. Dotted green: random phase approximation (RPA); dash-dotted blue: exact path integral Monte Carlo (PIMC) results20 using the full G(q, ω); dashed black: static approximation, i.e., setting Gstatic(q, ω) = G(q, 0); solid yellow: classical one-component plasma (OCP) at Γ = 1.92 (rs = 4) and at Γ = 4.8 (rs = 10); solid red: electronic pair alignment model [Eq. (1)] introduced in this work; the red arrows indicate the corresponding average red-shift compared to RPA. We can distinguish 3 distinct physical regimes: (I) λ ≫ d [collective], (II) λ ~ d [electronic pair alignment, two-particle excitations], and (III) λ ≪ d [single-particle]. The insets show PIMC and RPA results for the static structure factor S(q) and illustrate the absence of spatial structure at these conditions.
