SIMPLE SCHEME FOR THE NUMERICAL EVALUATION OF NEARLY SINGULAR-INTEGRALS

Nearly singular integrals are encountered in the evaluation of the Gre en's function for a variety of physical problems. One example is the e valuation of the electronic density of states in condensed matter phys ics. We propose a simple scheme for the accurate evaluation of a class of commonly encountered nearly singular integrals using panels of equ al width. This scheme is an extension of a method introduced by Roth [ Phys. Rev. B 7, 4321 (1973)]. We demonstrate the usefulness of the sch eme by employing it to evaluate the electronic density of states of a one- and of a three-dimensional ordered solid within a nearest neighbo r light binding model. A Fortran version of the scheme is also present ed. (C) 1997 American Institute of Physics.