  Recording field ion microscope images under field evaporating conditions and
subsequently reconstructing the underlying atomic configuration, called
three-dimensional field ion microscopy (3D-FIM) is one of the few techniques
capable of resolving crystalline defects at an atomic scale. However, the
quantification of the observed vacancies and their origins are still a matter
of debate. It was suggested that high electric fields (1-5 V/\r{A}) used in
3D-FIM could introduce artefact vacancies. To investigate such effects, we used
density functional theory (DFT) simulations. Stepped Ni and Pt surfaces with
kinks were modelled in the repeated slab approach with a (971) surface
orientation. An electrostatic field of up to 4 V/\r{A} was introduced on one
side of the slab using the generalized dipole correction. Contrary to what was
proposed, we show that the formation of vacancies on the electrified metal
surface is more difficult compared to a field-free case. We also find that the
electric field can introduce kinetic barriers to a potential
vacancy-annihilation mechanism. We rationalize these findings by comparing to
insights from field evaporation models.
