Identifying the ground state structures of point defects in solids

Point defects are a universal feature of crystals.Their identification is addressed by combining experimental measurements with theoretical models.The standard modelling approach is,however,prone to missing the ground state atomic configurations associated with energy-lowering reconstructions from the idealised crystallographic environment.Missed ground states compromise the accuracy of calculated properties.To address this issue,we report an approach to navigate the defect configurational landscape using targeted bond distortions and rattling.Application of our workflow to eight materials(CdTe,GaAs,Sb_(2)S_(3),Sb_(2)Se_(3),CeO_(2),In_(2)O_(3),ZnO,anatase-TiO_(2))reveals symmetry breaking in each host crystal that is not found via conventional local minimisation techniques.The point defect distortions are classified by the associated physico-chemical factors.We demonstrate the impact of these defect distortions on derived properties,including formation energies,concentrations and charge transition levels.Our work presents a step forward for quantitative modelling of imperfect solids.

High-throughput calculations of charged point defect properties with semi-local density functional theory— performance benchmarks for materials screening applications

Calculations of point defect energetics with Density Functional Theory(DFT)can provide valuable insight into several optoelectronic,thermodynamic,and kinetic properties.These calculations commonly use methods ranging from semi-local functionals with a-posteriori corrections to more computationally intensive hybrid functional approaches.For applications of DFT-based high-throughput computation for data-driven materials discovery,point defect properties are of interest,yet are currently excluded from available materials databases.This work presents a benchmark analysis of automated,semi-local point defect calculations with a-posteriori corrections,compared to 245“gold standard”hybrid calculations previously published.We consider three different a-posteriori correction sets implemented in an automated workflow,and evaluate the qualitative and quantitative differences among four different categories of defect information:thermodynamic transition levels,formation energies,Fermi levels,and dopability limits.We highlight qualitative information that can be extracted from high-throughput calculations based on semi-local DFT methods,while also demonstrating the limits of quantitative accuracy.