Valentyn Tatarenko

National Academy of Sciences of Ukraine | ISP · G. V. Kurdyumov Institute for Metal Physics

Наразі стрімко розвивається дослідження металевих розплавів в рамках кластерного уявлення про їхню будову. Однак до сих пір не до кінця зрозумілий механізм кластероутворення і не досліджено границі областей існування кластерів в рідині. В рамках нашої роботи досліджено механізми кластероутворення в моноатомних рідких металах під дією зовнішнього вп...

We report on the results obtained modelling the electronic and transport properties of single-layer graphene subjected to mechanical or magnetic fields and containing point defects. Reviewing, analyzing, and generalizing our findings, we claim that effects of uniaxial tensile strain or shear deformation along with their combination as well as struc...

Для з’ясування основних рис симетрійно-енергетичного та структурно-ентропійного аспектів взаємочину домішки та розчинника розвинуто конфіґураційний модель бездифузійного утворення «гібридного» твердого розчину втілення–заміщення Me–X, в якому взаємодійні атоми неметалу X можуть займати як октаедричні міжвузловини, так і вузли ОЦК(Т)-ґратниці металу...

Implementing the quantum-mechanical Kubo-Greenwood formalism for the numerical calculation of dc conductivity, we demonstrate that the electron transport properties of a graphene layer can be tailored through the combined effect of defects (point and line scatterers) and strains (uniaxial tension and shear), which are commonly present in a graphene...

The literature (experimental and theoretical) data on the tetragonality of martensite with interstitial–substitutional alloying elements and vacancies are reviewed and analysed. Special attention is paid to the studying the martensitic αʺ-Fe16N2-type phase with unique and promising magnetic properties as an alternative to the rare-earth intermetall...

The possibility of inducing a sizeable energy gap in the electronic structure of a graphene layer is still one of the biggest and most debated challenges in graphene electronics. Despite promising theoretical results, some experimental studies report the absence of a bandgap even in highly mechanically strained graphene. In this paper, we address t...

Harnessing the full potential of graphene for optoelectronic and electrochemical devices requires tunning and goal-directed control of its electronic properties. We report a computational study of the electron density of states and catalytic activity of graphene in the perpendicular magnetic field. We focus on the influence of uniaxial strain, cova...

The possibility of inducing a sizeable energy gap in the electronic structure of a graphene layer is still one of the biggest and most debated challenges in graphene electronics. Despite promising theoretical results, some experimental studies report the absence of a band gap even in highly mechanically strained graphene. In this paper, we address...

The chapter generalizes results on influence of external strain or/and magnetic fields on the electronic and transport properties of graphene with different kinds of imperfections (point defects, etc.): resonant (neutral) adsorbed atoms either oxygen-or hydrogen-containing molecules or functional groups, vacancies or their complexes with substituti...

Dissipative mechanism of formation of a modulated structure of vacancies in a body-centred cubic (b.c.c.) crystal is considered as its intrinsic property under an isothermal irradiation irrespectively of elastic-anisotropy factor sign. Conditions of self-organisation of a precursor of formation of a ‘superlattice’ of nanovoids, namely, the modulate...

The paper combines two theoretical approaches – the method of grazing dynamical diffraction (which allows performing the nondestructive structural diagnostics of defects in the near‐surface layers) with efficient numerical simulation method (which enables computation of electron structure in realistically large systems with millions of atoms) – for...

We study numerically a role of the uniaxial tensile strains and disordered defects in their impact on electronic density of states (DOS) in graphene exposed to an external magnetic field. The DOS curves are calculated using the tight-binding Hamiltonian, where the perpendicular magnetic field and uniaxial tension are included via the relevant modif...

This chapter generalizes results on the influence of uniaxial strain and adsorption on the electron states and charge transport or localization in graphene with different configurations of imperfections (point defects): resonant (neutral) adsorbed atoms, either oxygen- or hydrogen-containing molecules or functional groups, vacancies or substitution...

Spinodal mechanism of formation of a modulated structure in a spatial distribution of vacancies within the body-centred cubic (b.c.c.) crystal after irradiation is considered. The criterion of modulated-structure formation for the closed interacting-vacancies subsystem within the elastically anisotropic b.c.c. crystal is estimated. As shown, in cas...

We report a calculational study of electron states and the resulting electrochemical properties of uniaxially strained graphene with point defects. For this study the reduction of ferricyanide to ferrocyanide serves as a benchmark electrochemical reaction. We find that the heterogeneous electron transfer activity of the perfect graphene electrode r...

The main goal of our study was investigation of the influence of the deformations (sufficiently large for the establishing the non-zero gap) on electrotransport properties of impure graphene. To achieve this purpose, we implemented the simulation package that allows to perform numerical calculation of the conductivity and mobility of graphene sampl...

The study deals with electronic properties of uniaxially stressed mono- and multi-layer graphene sheets with various kinds of imperfection: point defects modelled as resonant (neutral) adsorbed atoms or molecules, vacancies, charged impurities, and local distortions. The presence of randomly distributed defects in a strained graphene counteract the...

The objective of this study is to calculate the parameters of strong exchange interactions within magnetic nanoparticles and weak (dipolar + anisotropic) interactions for the patterns of nanoparticles injected into non-magnetic substrate. The Fe–Pt magnetic system was chosen as the best applicable for this purpose. However, computations done in thi...

The concentration dependences of the magnetic properties of binary b.c.c. alloys with substitutional disorder are investigated within the scope of the generalized single-band Hubbard model. The breaking of alloys’ translation invariance because of the atomic disorder leads to a violation of electron–hole symmetry, which results in both the threshol...

A short historical review of stages of formation of the G. V. Kurdyumov Institute for Metal Physics (at the N.A.S. of Ukraine) in connection with its seventieth anniversary is presented. (According to both the decree of the Council of Peoples Commissars of the Ukrainian SSR of 15 November, 1945 and the decision of Presidium of the Academy of Scienc...

A kinetic model for the influence of external noises such as fluctuations of the vacancies’ generation rate and inhomogeneity of irradiated f.c.c. crystal on the formation of nanoscale modulated dissipative structure in a spatial distribution of vacancies is considered. The generation rate of vacancies all over the sites and a density of their disl...

Within the scope of the self-consistent-field (SCF) and mean-SCF approximations, the Matsubara–Kanzaki–Krivoglaz lattice-statics method as well as the Krivoglaz–Clapp–Moss approach, the kinematic diffuse scattering intensities near the Bragg reflection caused by the atomic short-range order (taking into account the long-range magnetic order) in a (...

As revealed, with the change of random spatial distribution of adatoms all over the graphene layer for correlated and ordered ones, the electroconductivity enhances in several (tens) times. Randomly arranged adatoms, which are attractive for uncombined charge carriers, manifest themselves as the long-range scattering centres, while they dominate as...

The review is concerned with studies of transformation of various types of atomic order during its relaxation from non-equilibrium state to equilibrium one and determination of microscopic parameters of migration of atoms, which characterize such relaxation in solid solutions (such as f.c.c.-Ni–Al alloys and С32-(Ti,W)B2 crystalline compounds). For...

Obstacles to the concept of an ideal diluted solution as a standard state, which has been widely used for a long time in physical metallurgy for statistical-thermodynamic treatments of interstitial solutions, are discussed. It is shown in this paper that partial molar entropy as a function of binary-solution con-centration is extremely sensitive to...

A kinetic model for the influence of external noises such as fluctuations of the vacancies’ generation rate and inhomogeneity of irradiated f.c.c. crystal on the formation of nanoscale modulated dissipative structure in a spatial distribution of vacancies is considered. The generation rate of vacancies all over the sites and a density of their disl...

A kinetic model for the influence of external noises such as fluctuations of the vacancies’ generation rate and inhomogeneity of irradiated f.c.c. crystal on the formation of nanoscale modulated dissipative structure in a spatial distribution of vacancies is considered. The generation rate of vacancies all over the sites and a density of their disl...

The chapter combines analytical (statistical-thermodynamic and kinetic) with numerical (Kubo-Greenwood-formalism-based) approaches used to ascertain an influence of the configurations of point (impurities, vacancies) and line (grain boundaries, atomic steps) defects on the charge transport in graphene. Possible substitutional and interstitial graph...

Electron-energy spectra and diagrams of magnetic-phase states of disordered b.c.c. binary substitutional alloys for various values of the parameter of elec-tron scattering by atoms of both constituents are investigated. To describe properties of these alloys, one-band tight-binding model taking into account electron-electron interactions in the cor...

The "IMP Science Gateway Portal" (http://scigate.imp.kiev.ua) for complex workflow management and integration of distributed computing resources (like clusters, service grids, desktop grids, clouds) is presented. It is created on the basis of WS-PGRADE and gUSE technologies, where WS-PGRADE is designed for science workflow operation and gUSE - for...

The chapter combines analytical (statistical-thermodynamic and kinetic) with numerical (Kubo-Greenwood-formalism-based) approaches used to ascertain an influence of the configurations of point (impurities, vacancies) and line (grain boundaries, atomic steps) defects on the charge transport in graphene. Possible substitutional and interstitial graph...

We consider the analytic peculiarities and singularities of various interactions between hydrogen-isotope (H, D) atoms located at tetrahedral interstices in an h.c.p. metal Me (Me = α-Y, α-Sc, α-Ti, α-Zr) taking into account its atomism, anisotropy of elasticity, and ‘size’ effect. The interaction between H (D) atoms, caused by distortions they ind...

Exchange integrals for f.c.c. Fe–Pt alloys in the whole platinum content range are estimated. Temperature dependences of spontaneous magnetizations of Fe and Pt subsystems for various platinum contents are obtained.

The method of the molecular dynamics is used in computer modelling of behaviour of freely based monolayer graphene membrane in the conditions of a nanoindentation inside an atomic-force microscope. Elastic properties and breaking strength are estimated for different physical conditions (nanoindenter velocity, nanoindenter head radius, nanoindenter...

Within the scope of the self-consistent-field (SCF) and mean-SCF approximations, the Matsubara–Kanzaki–Krivoglaz lattice-statics method as well as the Krivoglaz–Clapp–Moss approach, the kinematic diffuse scattering intensities near the Bragg reflection caused by the atomic short-range order (taking into account the long-range magnetic order) in a (...

Using the ab initio methods, boron or nitrogen doping effects on the characteristics of electron and vibrational spectrums of graphene are studied. We revealed that a mutual arrangement at the largest distance from each other is energy-preferred for these dopant atoms. Depending on their kind, one can regulate conductance and raise values of fundam...

Possible ordered distributions of carbon (C) and substituting dopant (A) atoms over the sites in a graphene-type lattice are considered for C2A- and C5A-type (super)structures (corresponding to stoichiometries of 1/3 and 1/6, respectively). Relaxation model of atomic long-range order (LRO) in a graphene-based lattice is developed, and kinetic curve...

In crystals under an irradiation, there can be a superlattice of nanopores. In a given work, conditions of self-organizing of a precursor of formation of a superlattice of nanopores, namely, the modulated structure in distribution of the vacancies generated by an irradiation because of instability of their homogeneous distribution as a result of in...

The global distributed computing infrastructure (DCI) on the basis of BOINC and Desktop Grids (DGs) technologies for high-performance distributed computing was used for porting the sequential molecular dynamics (MD) application to its parallel version for DCI with DGs and Service Grids (SGs) connected by EDGeS-bridge. It is shown that the mechanica...

Within the scope of the self-consistent field and mean (‘‘molecular’’) self-consistent field approximations, applying the static concentration wave method, the thermodynamics of f.c.c.-Ni–Fe alloys undergoing the static applied magnetic field effects is studied in detail. Under such conditions, the analytical corrections to expressions for the conf...

The effective vacancy–vacancy interaction is considered. Based on the continuum approximation for the Fourier components of strain-induced vacancy–vacancy interac-tion energies, approximating expressions for their expansion coefficients are obtained depending on the elasticity moduli, longitudinal and transverse phonon frequencies, and vacancy-conc...

The interatomic-interaction energies are calculated, and the spatial distributions of B or N impurity atoms in graphene lattice are predicted, using density functional theory and statistical-thermodynamic model, respectively. At least, at low temperatures, calculated energy parameters correspond to formation of stabile graphene-based CBc and CNc su...

We examine spatial distribution of the superparamagnetic core-shell spherelike impurity particles within the nematic host. Using a continuum model and the statistical-thermodynamic theory, we analyze the thermodynamic conditions necessary for modulated lamellar-structure to appear. There is a long-range effective interaction between the impurity pa...

A non-analyticity of the Fourier components, V̄ αα(k), of the inherently anisotropic, long-range and quasi-oscillating 'strain-induced' α-α-interaction energies, V αα), dependent on distances {r} between substitutional point defects in their solid solution based on finite f.c.c. crystal (with f .c.c. Ni as an example) is considered with regard for...

Within the scope of the self-consistent field and mean self-consistent ('molecular') field approximations, together with the static concentration waves' method, the statistical thermodynamics of f.c.c.-Ni-Fe alloys undergoing the static external magnetic field effects is studied in details. Under such conditions, the analytical corrections to the e...

As shown with using ab initio calculations, changing both the concentration of doping nitrogen or boron atoms and type of site substitution by them within the graphene lattice, it is feasible to regulate a conductivity of corresponding one-layer mixed C-N and C-B systems.

We examine the spatial distribution of rigid-sphere-like particles in a nematic host. Using a continuum model we analyse the conditions necessary for the appearance of a modulated lamellar structure. There is a long-range effective interaction between the particles, which can lead to the formation of superstructures. In general, this interaction in...

The statistical thermodynamics of a binary honeycomb-lattice gas is studied. The possible ordered distributions of substitutional atoms over the sites are predicted and a problem of their stability is analyzed. The ranges of values of interatomic-interaction parameters providing the low-temperature stability of the honeycomb-lattice-based superstru...

The review is concerned with studies of transformation of various types of atomic order during its relaxation from non-equilibrium state to equilibrium one and determination of microscopic parameters of migration of atoms, which characterize such relaxation in solid solutions (such as f.c.c.-Ni–Al alloys and С32-(Ti,W)B2 crystalline compounds). For...

The formation of the homogeneous magnetic short-range-ordered regions in disordered bcc-Fe0.5Co0.5 alloy under the influence of the electron-energy spectrum realignment with temperature is considered. For the description of electron states in a crystal, the multiband tight-binding model and the developed method for the cluster expansion of Green's...

The literary data on the structure, basic methods of fabrication, mechanical and electrical properties of nitrogen containing carbon nanotubes (N–CNT), which make possible its use in a nanotechnology, are summarized. Depending on the N–CNT configuration their thermodynamic stability is studied using the molecular dynamics and Monte-Carlo methods. P...

Using the statistical-thermodynamic methods within the scope of the self-consistent field approximation, an atomic ordering of the substitutional b.c.c.-Fe-Co alloy and the magnetic contribution of both its components (Fe and Co) in the interatomic interaction are investigated, and the temperature-concentration dependences of atomic order and magne...

Ordered distributions of carbon and substitutional dopant (A) atoms over the sites of a graphene lattice, i.e. CmA superstructures with dopant contents c=1/(m+1), and problem of their stability are considered theoretically. The ranges of values of interatomic-interaction parameters providing the low-temperature stability of the graphene-based C7A,...