First-principles simulation of ultrathin amorphous carbon films has been performed. Nanohybrid graphene-C60 systems were considered. Total energy calculations were performed using pseudopotential method within density functional theory. Local atomic structure and electronic energy spectrum of the systems were studied. It was demonstrated that fullerene-graphene interaction results in significant deformation of their local atomic structure. Obtained results are in good agreement with experimental X-ray UV spectra of hydrogenated amorphous carbon
Keywords: Phase-change resistive memory, ab-initio simulation, pseudopotential method, Kohn-Sham method, graphene, fullerenes, amorphous carbon, atomic structure, electronic structure, adsorption energy
Band structure calculations were performed for quasi-2D MeO systems using the pseudopotential method within density functional theory. The calculations were carried out within the plane waves methodology using pseudopotentials. Density of electron states was calculated within the approxination of collinear magnetism. We examined the electron structure and estimated the electronic and magnetic properties of FM-ordered quasi-2D MeO systems (Me = Mn, Fe, Co, Ni). It has been demonstrated that the MnO - FeO - CoO - NiO row exhibits a shift in 3d spin down states of the metal relatively to the Fermi level towards the low-energy region. The above affects magnetization in 2D systems of oxides of 3d transition metals. The character of electron density distribution in quasi-2D MeO systems (Me = Mn, Fe, Co, Ni) indicates ionic bond type between the atoms in Me systems. The tendency towards increase of the band gap in the FeO→ CoO→ NiO row has been established. The obtained estimates of the local magnetic moment of a 3d transition metal atom in crystals of examined oxides correlate with experimental data. In conformity with existing views in physics, we have revealed the effect of spontaneous spin polarization of Me 3d and 2p bands of oxygen atoms in quasi-2D MeO systems (Me = Mn, Fe, Co, Ni), which in our opinion plays the main role in generation of magnetic moments in the atoms of 3d transition metal and oxygen.
Keywords: Density functional theory, pseudopotential mathod, ferromagnetism, electronic band structure, transition metal oxides