  In a recent article, Wang et al (Phys. Chem. Chem. Phys., 22, 10624 (2020))
introduced a new class of interparticle potential for molecular simulations.
The potential is defined by a single range parameter, eliminating the need to
decide how to truncate truly long-range interactions like the Lennard-Jones
(LJ) potential. The authors explored the phase diagram for a particular value
of the range parameter for which their potential is similar in shape to the LJ
12-6 potential. We have reevaluated the solid phase behaviour of this model
using both Lattice Switch Monte Carlo and thermodynamic integration. In
addition to finding that the boundary between hexagonal close packed (hcp) and
face centred cubic (fcc) phases presented by Wang et al was calculated
incorrectly, we show that owing to its finite range, the new potential exhibits
several 'artifact' reentrant transitions between hcp and fcc phases. The
artifact phases, which do not occur in the full (untruncated) LJ system, are
also found for typically adopted forms of the truncated and shifted LJ
potential. However, whilst in the latter case one can systematically
investigate and correct for the effects of the finite range on the calculated
phase behaviour, this is not possible for the new potential because the choice
of range parameter affects the entire potential shape. Our results highlight
that potentials with finite range may fail to represent the crystalline phase
behaviour of systems with long-range dispersion interactions, even
qualitatively.
