Comment on “Curved-space Dirac description of elastically deformed monolayer graphene is generally incorrect”

In a recent paper [M. M. Roberts and T. Wiseman, Phys. Rev. B 105, 195412 (2022)], based on methods typical of the condensed-matter literature (the real-space gradient expansion applied to the tight-binding model), conclude that the curved-space Dirac description of the low-energy conductivity electrons of monolayer graphene is incorrect when only strain is present (elastic monolayer graphene). In this Comment we point out that, in a much earlier paper [A. Iorio and P. Pais, Phys. Rev. D 92, 125005 (2015)], basing our analysis on methods typical of quantum field theory in curved space-time, we had concluded the same. Unfortunately, the authors of [M. M. Roberts and T. Wiseman, Phys. Rev. B 105, 195412 (2022)] have missed that result (even though it is very clearly stated in various places, starting from the Abstract), to the extent of citing our paper as one where strain is actually used for that wrong purpose. Since the paper in point is written with the declared intent of bringing clarity into the debate, we believe that this Comment of ours is very much due, precisely to give it another try to achieve the latter purpose.