Completely Orthogonalized Plane Waves

Abstract

Orthogonalized plane waves (OPW's) are orthogonal to the core states by construction, but they are not mutually orthogonal. Furthermore, the set of all core states plus all OPW's is overcomplete. In this paper we construct a set of ``completely orthogonalized plane waves'' (COPW's) which share with OPW's the properties of being orthogonal to the core states and simply related to plane waves, but are superior to OPW's in that the set of all core states plus all COPW's is both orthonormal and complete (not overcomplete).