  Large-scale atomistic simulations with classical potentials can provide
valuable insights into microscopic deformation mechanisms and defect-defect
interactions in materials. Unfortunately, these assets often come with the
uncertainty of whether the observed mechanisms are based on realistic physical
phenomena or whether they are artifacts of the employed material models. One
such example is the often reported occurrence of stable planar faults (PFs) in
body-centered cubic (bcc) metals subjected to high strains, e.g., at crack tips
or in strained nano-objects. In this paper, we study the strain dependence of
the generalized stacking fault energy (GSFE) of {110} planes in various bcc
metals with material models of increasing sophistication, i.e., (modified)
embedded atom method, angular-dependent, Tersoff, and bond-order potentials as
well as density functional theory. We show that under applied tensile strains
the GSFE curves of many classical potentials exhibit a local minimum which
gives rise to the formation of stable PFs. These PFs do not appear when more
sophisticated material models are used and have thus to be regarded as
artifacts of the potentials. We demonstrate that the local GSFE minimum is not
formed for reasons of symmetry and we recommend including the determination of
the strain-dependent (110) GSFE as a benchmark for newly developed potentials.
