  Recently the structural transition in Na2Ti3Cl8 at 200 K with the formation
of triangular Ti3 clusters was studied by ab-initio calculations in PRL 124,
167203 (2020). It was concluded on the basis of the DFT+U results that the
usual band effects are not sufficient to explain this transition. The authors
then invoked magnetic mechanisms, including complicated factors such as
biquadratic and ring exchanges. We point out that this overcomplicated
description is unnecessary, and that the formation of trimers, or breathing
kagome lattice in Na2Ti3Cl8, and in many other systems, has very simple, almost
trivial explanation basing on the orbital-driven Peierls transition.
