  Non-bonded potentials are included in most force fields and therefore widely
used in classical molecular dynamics simulations of materials and interfacial
phenomena. It is commonplace to truncate these potentials for computational
efficiency based on the assumption that errors are negligible for reasonable
cutoffs or compensated for by adjusting other interaction parameters. Arising
from a metadynamics study of the wetting transition of water on a solid
substrate, we find that the influence of the cutoff is unexpectedly strong and
can change the character of the wetting transition from continuous to first
order by creating artificial metastable wetting states. Common cutoff
corrections such as the use of a force switching function, a shifted potential,
or a shifted force do not avoid this. Such a qualitative difference urges
caution and suggests that using truncated non-bonded potentials can induce
unphysical behavior that cannot be fully accounted for by adjusting other
interaction parameters.
