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arXiv · 1507.08815

Crystal structure optimisation using an auxiliary equation of state

Adam J. Jackson·Jonathan M. Skelton·Christopher H. Hendon·Keith T. Butler·Aron Walsh
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Abstract

Standard procedures for local crystal-structure optimisation involve numerous energy and force calculations. It is common to calculate an energy-volume curve, fitting an equation of state around the equilibrium cell volume. This is a computationally intensive process, in particular for low-symmetry crystal structures where each isochoric optimisation involves energy minimisation over many degrees of freedom. Such procedures can be prohibitive for non-local exchange-correlation functionals or other 'beyond' density functional theory electronic structure techniques, particularly where analytical gradients are not available. We present a simple approach for efficient optimisation of crystal structures based on a known equation of state. The equilibrium volume can be predicted from one single-point calculation, and refined with successive calculations if required. The approach is validated for PbS, PbTe, ZnS and ZnTe using nine density functionals, and applied to the quaternary semiconductor Cu$_{2}$ZnSnS$_{4}$ and the magnetic metal-organic framework HKUST-1.

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Adam J. Jackson, Jonathan M. Skelton, Christopher H. Hendon, Keith T. Butler, Aron Walsh. 2015-07-31. Crystal structure optimisation using an auxiliary equation of state. https://doi.org/10.1063/1.4934716

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