Comment on "Perturbation theory of scattering for grazing-incidence fast-atom diffraction", by W. Allison, S. Miret-Artés and E. Pollak, , 2022, , 15851.

In this comment we discuss some aspects of , 2022, , 15851, by Allison , an article intensely motivated by our study of grazing incidence fast atom diffraction (GIFAD) for He-KCl(001) [G. A. Bocan, H. Breiss, S. Szilasi, A. Momeni, M. E. Staicu Casagrande, M. S. Gravielle, E. A. Sánchez and H. Khemliche, , 2020, , 096101; G. A. Bocan, H. Breiss, S. Szilasi, A. Momeni, M. E. Staicu Casagrande, E. A. Sánchez, M. S. Gravielle and H. Khemliche, , 2021, , 235401]. In particular, (a) we show that, contrary to first order perturbation prediction, the surface corrugation is not proportional to the tangent of the rainbow angle and, (b) we analyze whether a Morse-like formula, like the one Allison use, is able to reproduce the atom-surface potential derived from density functional theory (DFT) calculations. In addition, we give some clarifications regarding specific remarks the authors made about our articles.