Evaluation of Some Fermi-Dirac Integrals

Abstract
The evaluation of Fermi‐Dirac integrals is discussed for cases in which the Sommerfeld method fails. Such cases occur when the integrand has a singularity at the Fermi surface and when the integrand is a rapidly oscillating function. As examples, the first‐order exchange integral for electrons and the free‐energy integral of the noninteracting electron gas in a magnetic field are evaluated. The method uses a contour‐integral representation of the Fermi function (previously mentioned by Dingle), supplemented by Mittag‐Leffler type expansions.