A comparative density functional theory investigation of the mechanical and energetic properties of ZnS

Using density functional theory, the elastic and energetic properties of zinc sulphide (ZnS) in the zinc blende and wurtzite solid phases have been calculated with several energy functionals within local density and generalised gradient approximations. We report on the plane-wave energy cut-offs (which determine the size of the basis sets) and k-point mesh density required to achieve energy convergence, and discuss the advantages of each functional with respect to computational expense and accuracy. This study provides a means of optimizing the trade-off between accuracy and computational expense due to the choice of energy functional used in further ab initio studies of ZnS systems, and may serve as a guide as to how one may undertake such testing in the case of other materials.