Accurate correlation energy functional for uniform electron gas from an interpolation ansatz without fitting parameters

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