Relationship between the Coulomb integralUand the Stoner parameterI

Orbital Hartree-Fock and the local spin density approximations to exchange are compared. The self-exchange intergrals calculated from the Hartree-Fock approximation are far larger than those calculated from the local spin density approximation. We suggest that, in metals where the exchange integrals are well shielded, a suitable functional for exchange may be obtained by scaling the orbital Hartree-Fock approximation to the local spin density approximation while retaining the stronger orbital dependence. Application to Fe and US produces good agreement with measurements.