Ab initio calculations of defects at surfaces

Charged defects at surfaces and interfaces play an important role in (opto)electronic devices, as these may induce large-scale electric fields, which may be essential or detrimental for device performance. Identifying the relevant defects and characterizing their properties is experimentally difficult. Theoretical calculations within density-functional theory aim at filling this gap. Yet, specific challenges arise in these calculations, not least by the challenge to link small-scale atomistic models to the device-scale electric effects. This becomes even more challenging as we move towards single-layer “2D” materials for future devices.

In my talk, I will summarize recent progress in overcoming artifacts that arise in periodic models (repeated-slab approach). I will demonstrate that current correction schemes allow to reduce numerical uncertainties well below systematic errors from the choice of the functional.