We report ab initio investigation of the adsorption (absorption) of atomic hydrogen on low-index ... more We report ab initio investigation of the adsorption (absorption) of atomic hydrogen on low-index surfaces, at symmetrical tilt grain boundaries and in the bulk for a series of titanium- and palladium-based alloys. The chemical bonding of hydrogen with transition metals is analyzed with respect to the surface composition and its orientation. The correlations between the absorption energy of hydrogen in bulk palladium alloys with 3d-5d elements and their electronic structure are discussed. A microscopic explanation of the local surface reactivity in the transition metal alloys is given. It was also shown that H atoms induce the weakening of the grain boundary cohesion in investigated materials.
Journal of Surface Investigation. X-ray, Synchrotron and Neutron Techniques, 2013
ABSTRACT Computer simulation of sapphire nitridation used to obtain nitride-based heterostructure... more ABSTRACT Computer simulation of sapphire nitridation used to obtain nitride-based heterostructures (GaN) on an Al2O3 substrate has been performed. The adhesion of atomic nitrogen to the sapphire (0001) surface is investigated ab initio. The possibility of replacing surface-layer oxygen atoms with nitrogen atoms has been examined. The calculated results indicate that adsorbed nitrogen atoms occupy the most stable positions above surface oxygen atoms at different nitrogen concentrations. The changes in the total system energy after replacement of surface oxygen atoms with nitrogen atoms have been calculated. It turns out that oxygen replacement is energetically unfavorable for a single nitrogen adatom. However, this process becomes energetically favorable if the concentration of nitrogen atoms increases. This outcome, obtained for the first time, enables better understanding of the atomic-scale mechanism of sapphire nitridation.
ABSTRACT The results of a theoretical study based on ab initio calculations of the polarization p... more ABSTRACT The results of a theoretical study based on ab initio calculations of the polarization properties of AlN, GaN, and AlGaN semiconductors with the wurtzite structure are presented. The values of the spontaneous and piezoelectric polarizations, as well as the piezoelectric constants, are calculated for these nitride compounds. With the aim of further considering prospective heterostructures based on (Al,Ga,AlGa)N compounds, the charge densities at the AlN/GaN, AlGaN/AlN, and AlGaN/GaN interfaces and carrier concentration at the AlGaN/GaN heterointerface is estimated and compared with the experimental data.
... [1] synthesized single walled carbon nanotubes by pulsed laser ablation at a temperature of 1... more ... [1] synthesized single walled carbon nanotubes by pulsed laser ablation at a temperature of 1200°C. The amount of synthesized nanotubes depended on the used catalyst in the following order: NiCo > Ni ~ NiFe Co ... Kiseleva, BP Tarasov, and VE Muradyan, Poverkhnost, No. ...
Journal of Experimental and Theoretical Physics, 2014
ABSTRACT We report on the results of ab initio calculations of vacancy and hydrogen-vacancy compl... more ABSTRACT We report on the results of ab initio calculations of vacancy and hydrogen-vacancy complexes in palladium and palladium hydride. Comparative analysis of the energies of the formation of defect complexes in palladium and its hydride has revealed that the formation of vacancy clusters is easier in the palladium hydride structure. Investigation of hydrogen-vacancy complexes in bulk crystalline palladium has shown that a hydrogen atom and a vacancy interact to form a stable hydrogen-vacancy (H-Vac) defect complex with a binding energy of E b = -0.21 eV. To investigate the initial stage in the formation of hydrogen-vacancy complexes (H n -Vac m ), we consider the clusterization of defects into clusters containing H-Vac and H2-Vac complexes as a structural unit. It is found that hydrogen-vacancy complexes form 2D defect structures in palladium in the (100)-type planes.
ABSTRACT An ab initio study of the features of the formation of the atomic structure of carbon ch... more ABSTRACT An ab initio study of the features of the formation of the atomic structure of carbon chains, which are structural parts of films of linear carbon chains, has been performed using the electron density functional theory. It has been shown that the formation and stabilization of experimentally observed kinks of carbon chains require the presence of hydrogen impurities in the chamber during the synthesis of linear carbon chains. The kinks of a carbon chain are formed in the process of the adsorption of hydrogen atoms on a chain. The optimal kink angle of carbon chains has been determined. The stability of kinks of carbon chains has been estimated as a function of the length of linear fragments. An additional mechanism has been proposed for the formation of kinks in carbon chains owing to the joining of short carbon chains with hydrogen ends.
Mathematical modeling in materials science of electronic component
Quantum-mechanical modeling of the magneto-optical properties of one-dimensional cobalt oxide nan... more Quantum-mechanical modeling of the magneto-optical properties of one-dimensional cobalt oxide nanowires formed on a stepped surface of platinum has been performed. Calculations have shown the relationship between the optical characteristics of surface cobalt oxide nanowires and their magnetic properties.
Using a quasi-ab initio molecular-dynamics method we have studied two-dimensional (2D) versus thr... more Using a quasi-ab initio molecular-dynamics method we have studied two-dimensional (2D) versus three-dimensional (3D) structures in Co clusters deposited on Cu(001) finding that the magnetism plays a relevant role. For the magnetic Co25 supported cluster, the influence of such a 2D to 3D structural change on the magnetic properties (magnetic-moment distribution an average magnetization) is investigated through self-consistent calculations within
We report ab initio investigation of the adsorption (absorption) of atomic hydrogen on low-index ... more We report ab initio investigation of the adsorption (absorption) of atomic hydrogen on low-index surfaces, at symmetrical tilt grain boundaries and in the bulk for a series of titanium- and palladium-based alloys. The chemical bonding of hydrogen with transition metals is analyzed with respect to the surface composition and its orientation. The correlations between the absorption energy of hydrogen in bulk palladium alloys with 3d-5d elements and their electronic structure are discussed. A microscopic explanation of the local surface reactivity in the transition metal alloys is given. It was also shown that H atoms induce the weakening of the grain boundary cohesion in investigated materials.
Journal of Surface Investigation. X-ray, Synchrotron and Neutron Techniques, 2013
ABSTRACT Computer simulation of sapphire nitridation used to obtain nitride-based heterostructure... more ABSTRACT Computer simulation of sapphire nitridation used to obtain nitride-based heterostructures (GaN) on an Al2O3 substrate has been performed. The adhesion of atomic nitrogen to the sapphire (0001) surface is investigated ab initio. The possibility of replacing surface-layer oxygen atoms with nitrogen atoms has been examined. The calculated results indicate that adsorbed nitrogen atoms occupy the most stable positions above surface oxygen atoms at different nitrogen concentrations. The changes in the total system energy after replacement of surface oxygen atoms with nitrogen atoms have been calculated. It turns out that oxygen replacement is energetically unfavorable for a single nitrogen adatom. However, this process becomes energetically favorable if the concentration of nitrogen atoms increases. This outcome, obtained for the first time, enables better understanding of the atomic-scale mechanism of sapphire nitridation.
ABSTRACT The results of a theoretical study based on ab initio calculations of the polarization p... more ABSTRACT The results of a theoretical study based on ab initio calculations of the polarization properties of AlN, GaN, and AlGaN semiconductors with the wurtzite structure are presented. The values of the spontaneous and piezoelectric polarizations, as well as the piezoelectric constants, are calculated for these nitride compounds. With the aim of further considering prospective heterostructures based on (Al,Ga,AlGa)N compounds, the charge densities at the AlN/GaN, AlGaN/AlN, and AlGaN/GaN interfaces and carrier concentration at the AlGaN/GaN heterointerface is estimated and compared with the experimental data.
... [1] synthesized single walled carbon nanotubes by pulsed laser ablation at a temperature of 1... more ... [1] synthesized single walled carbon nanotubes by pulsed laser ablation at a temperature of 1200°C. The amount of synthesized nanotubes depended on the used catalyst in the following order: NiCo > Ni ~ NiFe Co ... Kiseleva, BP Tarasov, and VE Muradyan, Poverkhnost, No. ...
Journal of Experimental and Theoretical Physics, 2014
ABSTRACT We report on the results of ab initio calculations of vacancy and hydrogen-vacancy compl... more ABSTRACT We report on the results of ab initio calculations of vacancy and hydrogen-vacancy complexes in palladium and palladium hydride. Comparative analysis of the energies of the formation of defect complexes in palladium and its hydride has revealed that the formation of vacancy clusters is easier in the palladium hydride structure. Investigation of hydrogen-vacancy complexes in bulk crystalline palladium has shown that a hydrogen atom and a vacancy interact to form a stable hydrogen-vacancy (H-Vac) defect complex with a binding energy of E b = -0.21 eV. To investigate the initial stage in the formation of hydrogen-vacancy complexes (H n -Vac m ), we consider the clusterization of defects into clusters containing H-Vac and H2-Vac complexes as a structural unit. It is found that hydrogen-vacancy complexes form 2D defect structures in palladium in the (100)-type planes.
ABSTRACT An ab initio study of the features of the formation of the atomic structure of carbon ch... more ABSTRACT An ab initio study of the features of the formation of the atomic structure of carbon chains, which are structural parts of films of linear carbon chains, has been performed using the electron density functional theory. It has been shown that the formation and stabilization of experimentally observed kinks of carbon chains require the presence of hydrogen impurities in the chamber during the synthesis of linear carbon chains. The kinks of a carbon chain are formed in the process of the adsorption of hydrogen atoms on a chain. The optimal kink angle of carbon chains has been determined. The stability of kinks of carbon chains has been estimated as a function of the length of linear fragments. An additional mechanism has been proposed for the formation of kinks in carbon chains owing to the joining of short carbon chains with hydrogen ends.
Mathematical modeling in materials science of electronic component
Quantum-mechanical modeling of the magneto-optical properties of one-dimensional cobalt oxide nan... more Quantum-mechanical modeling of the magneto-optical properties of one-dimensional cobalt oxide nanowires formed on a stepped surface of platinum has been performed. Calculations have shown the relationship between the optical characteristics of surface cobalt oxide nanowires and their magnetic properties.
Using a quasi-ab initio molecular-dynamics method we have studied two-dimensional (2D) versus thr... more Using a quasi-ab initio molecular-dynamics method we have studied two-dimensional (2D) versus three-dimensional (3D) structures in Co clusters deposited on Cu(001) finding that the magnetism plays a relevant role. For the magnetic Co25 supported cluster, the influence of such a 2D to 3D structural change on the magnetic properties (magnetic-moment distribution an average magnetization) is investigated through self-consistent calculations within
Uploads
Papers by D. Bazhanov