WANNIER-TYPE ORBITALS DERIVED FROM MULLIKENS POPULATION ANALYSIS

A simple scheme for obtaining well-localized non-orthogonal Wannier-ty pe orbitals (WTOs) for periodic systems is discussed. (The WTOs corres ponding to the same cell are orthogonal but the WTOs of different cell s are generally not.) The method uses the Magnasco-Perico localization criterion based on Mulliken's population analysis: Mulliken's net pop ulation corresponding to the elementary cell is extremized. The calcul ations require the system's density and overlap matrices which are ass umed to be known from a conventional band calculation but no explicit reference is made to the Bloch orbitals. The viability of the method i s illustrated with the example of 6-31G calculations for polyacetylene and polyglycine. (C) 1998 Elsevier Science B.V. All rights reserved.