Structure and electronic properties of crystals consisting of graphene layers $L_6$, $L_{4-8}$, $L_{3-12}$, and $L_{4-6-12}$

The structure and electronic properties of crystals consisting of graphene layers of four main polymorphic modifications, namely, $L_6$, $L_{4-8}$, $L_{3-12}$, and $L_{4-6-12}$, have been calculated in the framework of the density functional theory (DFT) using the generalized gradient approximation (GGA). The structural characteristics of individual layers and their relative positions that correspond to the minimum energy of interlayer bonds in the crystals have been found from the calculations. The electron densities of states and band structure of graphene crystals have been calculated. It has been established that crystals consisting of the main polymorphic modifications of graphene should exhibit metallic properties.