Automated effective band structures for defective and mismatched supercells

Abstract

In plane-wave density functional theory codes, defects and incommensurate structures are usually represented in supercells. However, interpretation of E versus k band structures is most effective within the primitive cell, where comparison to ideal structures and spectroscopy experiments are most natural. Popescu and Zunger recently described a method to derive effective band structures (EBS) from supercell calculations in the context of random alloys. In this paper, we present bs_sc2pc, an implementation of this method in the CASTEP code, which generates an EBS using the structural data of the supercell and the underlying primitive cell with symmetry considerations handled automatically. We demonstrate the functionality of our implementation in three test cases illustrating the efficacy of this scheme for capturing the effect of vacancies, substitutions and lattice mismatch on effective primitive cell band structures.

Effect of oxygen and nitrogen functionalization on the physical and electronic structure of graphene

“…The structures were visualized using Jmol, an open-source Java viewer for chemical structures in 3D (http://www.jmol.org/). The effective band structures were derived following the method described by Popescu and Zunger [47,48] using bs_sc2pc [49], a recently implemented add-on released with the academic release of CASTEP 7.0. Nano Res.…”

Phonon dispersion unfolding in the presence of heavy breaking of spatial translational symmetry

“…The main advantage of this method is the ability to handle systems with heavy breaking of spatial translational symmetry. Its validity is tested by pure diamond, diamond with Si substitution, and diamond with C vacancies.Since the discovery of effective energy bands in semiconductors [1,2] and alloys [3], unfolding methods for treating the electronic band structures of the weakly periodic solid systems have been rapidly developed [4][5][6][7][8][9][10][11][12][13][14]. Moreover, it has also stimulated the study of phonon dispersion unfolding method [14][15][16][17].…”

Unfolding phonon spectra by smearing of vibrational eigenmodes

“…j 1 (r) being the spherical Bessel function. The plane wave representation (10) for Ψ sQ as well as (12) for C (s) G (Q) allows the expression for the weights to be written down in the same way as in [8,14,18]…”