  Based on the results of first-principles calculations we demonstrate that
significant distortion of graphene sheets caused by adsorption of fluorine
atoms leads to the formation of metastable patterns for which the next step of
fluorination is considerably less energetically favorable. Existence of these
stable patterns oriented along the armchair direction makes possible the
synthesis of various CFx structures. The combination of strong distortion of
the nonfluorinated graphene sheet with the doping caused by the polar nature of
C-F bonds reduces the energy cost of migration and the energy of migration
barriers, making possible the migration of fluorine atoms on the graphene
surface as well as transformation of the shapes of fluorinated areas. The
decreasing energy cost of migration with increasing fluorine content also leads
to increasing numbers of single fluorine adatoms, which could be the source of
magnetic moments.
