Structure and electronic properties of polymorphic types of fluorographene

The density functional theory in the gradient approximation has been used to calculate the structure and the electronic properties of five major polymorphic types of fluorographene in which the carbon atoms are in the equivalent structural states. The crystal lattice of a layer of the first structural type refers to the hexagonal system, its unit cell contains two fluorine atoms and two carbon atoms. The remaining structural forms of fluorographene have the crystal lattices corresponding to the orthorhombic syngony, their unit cells contain 8 or 16 atoms. The layer density of the fluorographene polymorph varies from 1.557 to 1.821 mg/m${}^2$, which is approximately twice the density of the graphene layers 0.74 mg/m${}^2$. As a result of calculations of the band structure and the density of electronic states, it was established that the width of the band gaps at the Fermi level for the structural types of fluorographene varies from 3.04 eV to 4.19 eV. The sublimation energy of the fluorographene polymorph types in the range from 14.08 to 14.32 eV/CF. This indicates the possibility of the stable existence of the fluorographene basic structural varieties under standard conditions.