Ab initio method for calculating response functions in transition metals.

Abstract

We present a new approach for calculating charge- and spin-density response functions in transition metals from first principles, using tight-binding linear muffin-tin orbitals as basis functions. It is advantageous to use a partitioning in terms of small and large reciprocal-lattice vectors and to treat only the former exactly. We show that for the set of large reciprocal-lattice vectors, the dielectric matrix becomes separable, because only the plane-wave matrix elements between orbitals at the same lattice site contribute. Our method allows the evaluation of the electronic self-energy of transition metals within the GW approximation of Hedin [Phys. Rev. 139, A796 (1965)].