Analytical approximation of the Fermi-Dirac integrals of half-integer and integer orders

Abstract

We have obtained continuous analytical expressions approximating the Fermi-Dirac (F-D) integrals of orders j = −1/2, 1/2, 1, 3/2, 2, 5/2, 3, and 7/2 in a convenient form for calculation with reasonable accuracy (1–4)% in a wide degeneration range in this paper. An approach based on the least squares method for approximation was used. The demands for the approximation of integrals, the range of variation of order j, and the definitional domain are considered in terms of the use of F-D integrals to determine the properties of metals and semiconductors.