  We report an analytical representation of the correlation energy ec(rs, zeta)
for a uniform electron gas (UEG), where rs is the Seitz radius or density
parameter and zeta is the relative spin polarization. The new functional,
called W20, is constructed to capture the known high-density and low-density
limit (for zeta = 0 and 1) without any fitting parameters. The comparative
assessment against the recent quantum Monte Carlo (QMC) results shows that the
performance of the W20 functional is comparable to the popular parametrized UEG
correlation functionals. On average, W20 agrees with QMC and PW92 [Phys. Rev. B
45, 13244 (1992)] within 0.01 eV, and W20 recovers the correct high- and
low-density limits, whereas the QMC-data fitted UEG correlation functionals do
not.
