The structure and the electronic properties of graphic monofluoride (C
F)n have been studied within the framework of the density-functional t
echnique, using nonlocal ionic pseudopotentials and a large number of
plane waves. The chair conformation is shown to be energetically favor
ed with respect to the boat conformation by 0.145 eV per CF unit. The
transition between these two states has been investigated: the boat co
nformation is metastable, with an estimation of the transition barrier
on the order of 2.72 eV. This indicates that the material actually sy
nthesized could depend on the kinetics of the intercalation or could a
s well be a mixing of both conformations. The equilibrium geometries a
re compared with experimental data. We also present the valence charge
density and the band structure of the chair conformation.