Ab Initio Calculations of Carbon Bilayers with Diamond-Like Structures

Abstract

Ab initio calculations of monoatomic and diatomic carbon layers composed of four-coordinated (sp3 hybridized) atoms are reported. According to the calculations, monoatomic diamond-like layers L4, L3–6, and L3–4–6 are unstable even at a temperature of 0 K. The structure of diatomic layers can be formed by the polymerization of hexagonal graphene layers. The analysis of all possible ways of cross-linking graphene layer pairs shows that only one diatomic layer can be stable. The crystal lattice of this layer belongs to the p6/mmm symmetry group (four atoms in a hexagonal unit cell, a = 2.737 A). The surface density, sublimation energy, and direct band gap values of the layer are 0.123 µg/cm2, 6.64 eV/atom, and 3.37 eV, respectively. The hexagonal structure of the diamond-like layer is predicted to be stable up to 250 K at normal pressure. The powder XRD pattern of the diamond-like layers is calculated to be used for their experimental identification in carbon materials.