Simulation of optical spectra of novel Tl 4 CdI 6 and Tl 4 HgI 6 optoelectronic crystals

The results of calculations using local density approximation and generalized gradient approximation: the total energy depending on the volume of the unit cell, the distribution of the total density of states and the partial contributions of electronic orbitals in the band structure of Tl 4 CdI 6 and Tl 4 HgI 6 crystals are shown in this paper. The spectra of the real part of the dielectric permittivity, the spectra of the imaginary part of permittivity, the reflection spectra and the absorption coefficient of both crystals are obtained using the Kramers-Kronig method. A comparative analysis of theoretical calculations with experimental data is carried out. Substantial influence of electron-phonon broadening is shown

Simulation of optical spectra of novel Tl4CdI6 and Tl4HgI6 optoelectronic crystals

The results of calculations using local density approximation and generalized gradient approximation: the total energy depending on the volume of the unit cell, the distribution of the total density of states and the partial contributions of electronic orbitals in the band structure of Tl4CdI6 and Tl4HgI6 crystals are shown in this paper. The spectra of the real part of the dielectric permittivity, the spectra of the imaginary part of permittivity, the reflection spectra and the absorption coefficient of both crystals are obtained using the Kramers–Kronig method. A comparative analysis of theoretical calculations with experimental data is carried out. Substantial influence of electron–phonon broadening is shown

Дослідження з перших принципів сенсорних властивостей нанотрубок оксиду цинку

A density functional theory study of the adsorption of various gas molecules (O2, H2O, CO, NH3, CH3OH and C2H5OH) on a ZnO nanotubes (NTs) were performed. We determine their exact orientation on the NT wall and their preferential binding site by calculating their binding energy. Their charge transfer to the NT wall is investigated in order to determine the donor or acceptor character of the molecular adsorbates. Particular attention is paid to understanding the modification of electronic structures of ZnO NTs by the gas-molecule adsorbates.В рамках теории функционала плотности проведено исследование адсорбции молекул различных газов (O2, H2O, CO, NH3, CH3OH и C2H5OH) на поверхности нанотрубок ZnO. На основе вычисленных значений энергии связи определены оптимальные конфигурации молекул на поверхности нанотрубок. С целью установления какой донорный или акцепторный характер имеет молекулярная адсорбции определена степень переноса заряда на нанотрубки.У межах теорії функціоналу густини проведено дослідження адсорбції молекул різних газів (O2, H2O, CO, NH3, CH3OH і C2H5OH) на поверхні нанотрубок ZnO. На основі обчислених значень енергії зв’язку визначено оптимальні конфігурації молекул на поверхні нанотрубок. З метою встановлення донорний чи акцепторний характер молекулярної адсорбції визначено ступінь перенесення заряду на нанотрубк

Argand diagram and oscillator strength of In_0.5Tl_0.5I crystal

The dynamics of the electron subsystem parameters in In&lt;sub&gt;0.5&lt;/sub&gt;Tl&lt;sub&gt;0.5&lt;/sub&gt;I substitutional solid solutions has been studied theoretically using of the pseudopotential method. According to Kramers-Kronig method there have been determined the optical functions of the multilayer In0,5Tl0,5I for the different light polarizations in a broad energy range (0 - 15 eV). The energies of oscillators were defined from the Argand diagrams. The main oscillator settings transitions has been determined.Keywords: substitutional solid solutions, dielectric function, oscillator, Argand diagrams, polarization.</p

Specific Features of Content Dependences for Energy Gap in InxTl1−xIIn_{x}Tl_{1-x}I Solid State Crystalline Alloys

A series of $In_{x}Tl_{1-x}I$ (x=0.4-0.9) single crystalline solid state alloys were successfully synthesized by the vertical Bridgman method. For the first time the density functional theory based band structure calculations are performed and features of the band energy dispersion are discussed. Comparison with the experimental energy gap $E_{g}$ obtained from the optical photoconductivity is discussed. An essential role of the localized defects and excitons in formation of the edge photoconductivity is analyzed. Relation between the crystal structure and photoconductivity of the materials studied is discussed. Also the origin of the principal valence and conduction bands is explored. Experimental measurements of the band gap $E_{g}$ by the optical and photoconductivity methods have given opposite dependences with respect to the indium content x. Features of the photoconductivity spectra for different crystallographic directions have been discussed with taking into account the chemical bonds anisotropy