Three-dimensional structure and electronic properties of crystals formed from layersof fluorine functionalized hexagonal graphene

The simulation of the three-dimensional structure of fluorographene crystals was carried out by the method of atom-atomic potential. Fluorinated graphene crystals were formed from five different polymorphic varieties of fluorine functionalized hexagonal graphene. As a result of calculations, it was found that the interlayer distance in crystals varies in the range from 0.4727 to 0.5745 nm. The relative shift of adjacent layers, at which the minimum of the interlayer bond energy is observed, varies from zero, for T1 type crystals, to a maximum value equal to 0.1683 nm in T4 type crystals. The calculated density of fluorographene crystals varies from 3.233 to 3.975 g/cm${}^3$. As a result of calculations of the electronic structure performed by the density functional theory method, it was established that the band gap varies from 2.505 eV in CF crystals of the T1 structural type to 3.666 eV in T4 crystals. The band gap for different structure types in three-dimensional fluorographene crystals is 0.276–0.594 eV less than the band gap for the corresponding isolated monolayers of fluorinated hexagonal graphene.