Short-range correlation in the uniform electron gas: Extended Overhauser model

We use the two-electron wave functions (geminals) and the simple screened Coulomb potential proposed by Overhauser [Can. J. Phys. 73, 683 (1995)] to compute the pair-distribution function g(r) for a uniform electron gas, finding the exact g(0) for this model and extending the results from g(0) to g(r), We find that the short-range (r<r(s)) part of this g(r) is in excellent agreement with quantum Monte Carlo simulations for a wide ran-e of electron densities. We are thus able to estimate the value of the second-order (r(2)) coefficient of the small interelectronic-distance expansion of the pair-distribution function. The coefficients of the small-r expansion of the spin-resolved g(<sigma>sigma')(r) have density or r(s) dependencies which we parametrize in a way that makes it easy to find their coupling-constant averages. Their spin-polarization or zeta dependencies are estimated from a proposed spin-scaling relation.