2D electron gas at arbitrary spin polarizations and coupling strengths: exchange-correlation energies, distribution functions, and spin-polarized phases.

We use the classical mapping of quantum fluids [Phys. Rev. Lett. 84, 959 (2000)] for a study of the uniform 2D electron gas. The "quantum temperature" T(q) of the classical 2D Coulomb fluid having the same correlation energy E(c) as the quantum fluid is determined as a function of the density parameter r(s). Using this T(q), spin-dependent pair-distribution functions are determined, and an analytic fit to the E(c) is given. The T(q) for 2D and 3D electron fluids is found to be approximately the same universal function of the classical coupling constant Gamma. The coupling Gamma increases more rapidly with density in 2D; hence, we present a scheme for including bridge terms in the 2D hypernetted-chain method. The Helmholtz free energies of the spin-polarized and unpolarized phases are calculated, and the existence of a ferromagnetic phase near r(s) approximately 30 is found to be a marginal possibility.