No abstract

The model of electron gas situated on the two-dimensional continual cylindrical surface is suggested to describe a polaron in the single-walled nanotube made of polar material. The problem on weak-coupling polaron is solved using perturbation theory. Analytical expression for the polaron energy shift of the subband is found in the case of bulk phonon approximation and the case when longitudinal optical (LO) phonons are confined on the cylinder's surface. It is shown that in the second case the polaron effect is negligible.

No abstract

No abstract

The results of studying the electronic structure and the influence of the local environment of the copper impurity on the properties and magnetic moment in supercells in Zn1-xCuxO are presented. DFT calculations were carried out in the local electron density (LDA) and generalized gradient approximation (GGA). The band structure of in Zn1-xCuxO was calculated taking into account the correction for spin polarization and the strong electronic interaction. DFT LSDA + U and SGGA + U (U is the Coulomb interaction) calculations made it possible to take into account the contributions of the 3d shells of the Zn and Cu cations to the band spectrum of in Zn1-xCuxO. The introduction of copper into the ZnO lattice leads to a change in the impurity and valence bands of in Zn1-xCuxO. In this case, the bottom of the in Zn1-xCuxO conduction band shifts towards low energies. The total density of electronic states of in Zn1-xCuxO near the Fermi level is mainly determined by the 3d states of Zn and Cu and the 2p state of oxygen. ZnO doped with copper acquires a magnetic moment. The introduction of a vacancy into a supercell in Zn1-xCuxO noticeably changes the local magnetic moment. As the copper concentration in Zn1-xCuxO (x=0, 0.01, and 0.02) increases, the conductivity of the samples in both constant and alternating current increased, and the activation energy of conduction decreased. Keywords: ZnO, copper doping, density functional theory, band calculations, electronic structure, localized magnetic moment, defect formation energies, Zn1-xCuxO, charge transfer, parameters of localized states.