title: Muffin-tin orbital Wannier-like functions for insulators and metals.
abstract: Herein, we outline a method that is able to generate truly minimal basis sets that accurately describe either a group of bands, a band, or even just the occupied part of a band. These basis sets are the so-called NMTOs, muffin-tin orbitals of order N. For an isolated set of bands, symmetrical orthonormalization of the NMTOs yields a set of Wannier functions that are atom-centered and localized by construction. They are not necessarily maximally localized, but may be transformed into those Wannier functions. For bands that overlap others, Wannier-like functions can be generated. It is shown that NMTOs give a chemical understanding of an extended system. In particular, orbitals for the pi and sigma bands in an insulator, boron nitride, and a semimetal, graphite, will be considered. In addition, we illustrate that it is possible to obtain Wannier-like functions for only the occupied states in a metallic system by generating NMTOs for cesium. Finally, we visualize the pressure-induced s-->d transition.
authors.affiliation: Max-Planck-Institut für Festkörperforschung, Heisenbergstrasse 1, 70569, Stuttgart, Germany. e.zurek@fkf.mpg.de
authors.forename: Eva
authors.initials: E
authors.lastname: Zurek
authors.forename: Ove
authors.initials: O
authors.lastname: Jepsen
authors.forename: Ole Krogh
authors.initials: OK
authors.lastname: Andersen