V. G. Mazurenko

Study of the electro-absorption spectrum of a nickel acceptor exciton in a ZnO:Ni crystal based on a calculation of vibrations associated with a Ni+1 impurity

Localized vibrations in ZnO crystals due to the substitution impurity Ni+1 are modeled. The calculations were performed in the shell model using a recursive method for vibrations with A1 and E type symmetry. Numerical calculations allowed us to analyze the vibronic structure in the electro-absorption spectra for nickel acceptor excitons in ZnO:Ni.

A vibronic-structure analysis of optical spectra in ZnO:Ni3+ crystals by localized-vibration simulation

A theoretical study is reported of the vibrations associated with a Ni3+ impurity charged with respect to the ZnO lattice. The calculations were made by a recursive method in terms of the shell model for vibrations with different symmetries. The vibronic structure observed in the spectra of d-d intracenter transitions in the Ni3+ impurity has been interpreted using model calculations.

Interaction of nickel donor and acceptor excitons with defect vibrations in ZnSe:Ni crystals

Defect vibrations in ZnSe:Ni crystals induced by the Ni impurity with charge of ±1 relative to the neutral state are calculated by a recursive method in the shell model. This leads to an interpretation of vibronic structures in electroabsorption spectra for donor and acceptor Ni excitons in ZnSe:Ni crystals.

Ab initio calculations of the vibrational spectra of 1/1 approximant of i-AlCuFe quasicrystal

The partial and total densities of vibrational states of the 1/1 crystal approximant of the icosahedral i-AlCuFe quasicrystal are calculated using the method of pseudopotentials in the generalized gradient approximation (to describe the electronic states) and the frozen-phonon method (to determine the dynamic matrix). The results obtained agree well with experimental inelastic neutron scattering data, which indicates that the method of calculations is appropriate and could be used to calculate other crystal approximants.

Model of the lattice dynamics and study of the vibronic structure of intracenter transitions in ZnO:Ni+2 crystals

This paper presents a calculation of the defect vibrations induced in a ZnO:Ni crystal by the Ni+2 impurity. The computations are done by a recursive method in the shell model. Based on the model calculations, the vibronic structure in the absorption spectra of the intracenter d-d transitions in the ZnO:Ni crystal is interpreted.

Simulation of vibrational spectra of SiO2 nanoclusters

The vibrational density of states of α-SiO2 nanoclusters with different diameters has been calculated in terms of the shell model in the harmonic approximation. A decrease in the diameter of nanoparticles leads to an increase in the vibrational density of states in the low-frequency range of the spectrum, a shift of the spectrum in the high-frequency range, and the generation of gap vibrational modes. The interpretation of the observed features has been proposed.

Structural features and atomic dynamics in Si/SiO2 superlattices: First-principles calculations

The crystal structure and atomic dynamics of Si/SiO2 superlattices based on silicon in the diamond and β-cristobalite lattices have been investigated. The two basic models for the description of interfaces in the system under investigation, i.e., the double-bonded model and the bridge-oxygen model, have been considered. It has been shown that the atomic structure of the lattices substantially changes during the relaxation as compared to ideal model structures. An analysis of the vibrational spectra has demonstrated that, in the high-frequency spectral range (600–1200 cm−1), there appear vibrational modes that have no dispersion in the direction of the lattice growth. The absence of vibrations characteristic of silicon and β-cristobalite in the spectra of the superlattices indicates that their formation occurs at the interfaces and that a particular frequency dependence is determined by the redistribution of atoms in this region.

Simulation of the lattice dynamics of an Al-Cu-Fe icosahedral quasicrystal

The total and partial vibrational spectra of aluminum, copper, and iron atoms in an Al-Cu-Fe icosahedral quasicrystal are calculated by the recursive method. The calculations are based on the 1/1 crystal approximant. The interaction of atoms in the Al-Cu-Fe quasicrystal is described within the EAM model. The calculated spectra are in satisfactory agreement with the experimental data on neutron inelastic scattering.

The origin of localized vibrations in KI: Cl and KI: H crystals

The resonant, gap, and local vibrational modes of Cl and H impurities in KI crystals are calculated recursively using the shell model. The contributions from ions located in various coordination shells around the impurity to the formation of localized vibrations are studied. The results of the calculations are in satisfactory agreement with the experimental data.

Calculation of the vibrational spectra of copper crystals with vacancies

The local vibrational spectra of copper crystals containing vacancies are calculated using the pair atomic potential derived in the framework of the resonance pseudopotential theory. The calculations are performed by a recursive method with due regard for the symmetry of the defect region. The frequencies of the vacancy-induced resonance vibrations of different symmetries are determined.