Harmonically trapped fermion gases: exact and asymptotic results in arbitrary dimensions

Abstract

We investigate the particle and kinetic energy densities of harmonically trapped fermion gases at zero temperature in arbitrary dimensions. We derive differential equations connecting these densities, which so far have been proved only in one or two dimensions, and give other interesting relations involving several densities or the particle density alone. We show that in the asymptotic limit of large particle numbers, the densities go over into the semi-classical Thomas-Fermi (TF) densities. Hereby the Fermi energy to be used in the TF densities is uniquely identified. We derive an analytical expansion for the remaining oscillating parts and obtain very simple closed forms for the leading-order oscillating densities. Finally, we show that the simple TF functional relation Τ_TF[ρ] between kinetic and particle densities is also fulfilled for the asymptotic quantum densities Τ(r) and ρ(r) including their leading-order oscillating terms.