Kravchenko K. Vibrational and electronic characteristics of the hetero-geneous systems with strong anisotropy of the interatomic interaction

The features of the spectrum and frequency spacing of graphite, in which the phonon spectrum has quasi-two-dimensional character, are defined. The physical reasons of the flexural rigidity in graphene monolayers are analysed. The singularity of the spectral density of quasi- bending fluctuations of graphite is revealed. This singularity is similar to the Dirac one in the electronic spectrum of graphene and the conditions of quasi-localized states formation near the singularity. The conditions of formation of Ioffe-Regel phonon crossovers in layered crystals are determined. It is shown that the structure of bigraphen is resistant against temperature growth up to values which exceed the room temperature.