Band unfolding made simple

Abstract

We present a simple view on band unfolding of the energy bands obtained from supercell calculations. It relies on the relationship between the local density of states in reciprocal space and the fully unfolded band structure. This provides an intuitive and valid approach not only for periodic, but also for systems with no translational symmetry. By refolding into the primitive Brillouin zone of the pristine crystal we recover the conventional unfolded bands. We implement our algorithm in the Siesta package. As an application, we study a set of benchmark examples, ranging from simple defects on crystals to systems with increasing complexity and of current interest, as the effect of external pressure on rotated graphene bilayers.