Collective behaviors of an electron gas in the mean-field regime
Dong Hao Ou Yang
TL;DR
The paper derives a rigorous mean-field description of the momentum distribution for an electron gas on a 3D torus in the high-density limit, using a trial state $\Psi_N=e^{-\mathcal{K}}\Psi_{FS}$ built on a Slater determinant. It splits the momentum occupation into bosonization and exchange-correlation components, obtaining explicit formulas and sharp error bounds that hold for a broad class of singular interactions with square-summable Fourier modes. A bootstrap argument controls the key auxiliary quantity $\mathcal{Q}$, leading to $\mathcal{Q}=O(k_F^{-1/2+\delta})$, and yielding overall error $\mathcal{O}(k_F^{-3/2+\delta})$ in the momentum observable $n(f)$. The results generalize prior high-density/metallic-density analyses (Daniel–Vosko, Lam) to a wider potential class, connect with recent work on mean-field momentum distribution, and provide a rigorous framework for understanding collective excitations and exchange effects beyond the Hartree–Fock picture in the mean-field regime.
Abstract
In this paper, we study the momentum distribution of an electron gas in a $3$-dimensional torus. The goal is to compute the occupation number of Fourier modes for some trial state obtained through random phase approximation. We obtain the mean-field analogue of momentum distribution formulas for electron gas in [Daniel and Voskov, Phys. Rev. 120, (1960)] in high density limit and [Lam, Phys. Rev. \textbf{3}, (1971)] at metallic density. Our findings are related to recent results obtained independently by Benedikter, Lill and Naidu, and our analysis applies to a general class of singular potentials rather than just the Coulomb case.
