Comment on “Path to collapse for an isolated Néel skyrmion”

Rohart et al. [Phys. Rev. B 93, 214412 (2016)] recently reported calculations indicating two mechanisms for the annihilation of a skyrmion in a Co monolayer on Pt(111). The path calculations were based on a method presented in the Supplemental Material of their article. It is pointed out here that their method does not in general converge on minimum energy paths unlike the geodesic nudged elastic band method which is discussed for comparison. As a result, the maximum energy along the two paths presented does not provide an accurate estimate of the activation energy for the transition and the fact that two different paths were obtained should not be taken as an indication that the skyrmion annihilation can occur by two different mechanisms.