Effect of charge on point defect size misfits from ab initio: Aliovalently doped SrTiO3SrTiO3

• The size misfits of multiple defects are computed efficiently using isolated defects.
• The size misfits of isolated defects have different linear dependencies on charge state.
• The extra electron/hole from a charged defect is delocalized around the defect site.

We demonstrate a computationally efficient method to calculate size misfits of point defects in aliovalently doped SrTiO3SrTiO3 using density functional theory. The size misfits of neutral and charged single point defects are calculated and linearly combined to estimate the effective size misfits of multiple point defects in aliovalently doped SrTiO3SrTiO3. The charge state has a demonstrable effect on point defect size misfits for both isolated and multiple defects. We attribute this to the different charge localization between the defective systems. The extra electron or hole for the charged isolated point defects compensates the difference of charge localization between the neutral point defects and aliovalently doped system. The sum of size misfits of charged isolated point defects accurately estimates size misfits for aliovalently doped SrTiO3SrTiO3, without charge correction which was possibly required due to the additional charge state of point defect.

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