  A new simulation approach of field evaporation is presented. The model
combines classical electrostatics with molecular dynamics (MD) simulations.
Unlike previous atomic-level simulation approaches, our method does not rely on
an evaporation criterion based on thermal activation theory, instead,
electric-field-induced forces on atoms are explicitly calculated and added to
the interatomic forces. Atoms then simply move according to the laws of
classical molecular dynamics and are "evaporated" when the external force
overcomes interatomic bonding. This approach thus makes no ad-hoc assumptions
concerning evaporation fields and criteria, which makes the simulation fully
physics-based and "ab-initio" apart from the interatomic potential. As proof of
principle, we perform simulations to determine material dependent critical
voltages which allow assessing the evaporation fields and the corresponding
steady-state tip shapes in different metals. We also extract critical
evaporation fields in elemental metals and sublimation energies in a high
entropy alloy to have a more direct comparison with tabulated values. In
contrast to previous approaches, we show that our method is able to
successfully reproduce the enhanced zone lines observed in experimental field
desorption patterns. We also demonstrate the need for careful selection of the
interatomic potential by a comparative study for the example of Cu-Ni alloys.
