Title: Comment on "Spatial optical solitons in highly nonlocal media" and related papers,
Abstract: In a recent paper [A. Alberucci, C. Jisha, N. Smyth, and G. Assanto, Phys.
Rev. A 91, 013841 (2015)], Alberucci et al. have studied the propagation of
bright spatial solitary waves in highly nonlocal media. We find that the main
results in that and related papers, concerning soliton shape and dynamics,
based on the accessible soliton (AS) approximation, are incorrect; the correct
results have already been published by others. These and other inconsistencies
in the paper follow from the problems in applying the AS approximation in
earlier papers by the group that propagated to the later papers. The accessible
soliton theory cannot describe accurately the features and dynamics of solitons
in highly nonlocal media.