List of Departments
Topmost Scientific Results
🗀 Archive 2010-2015
Department of Computational Methods in Theoretical Physics
- The model of migration processes in the crystalline matrix of cadmium iodide with isomorphic lead iodide nanoinclusions has been developed. Stoichiometric effect on the processes of charge carrier trapping has been analyzed. It was found that one of the possible mechanisms of photoelectret state formation in this system is associated with orientational polarization of nonlinear lead iodide molecule.N.V. Gloskovska
- We present a broad palette of discussions of the concepts of a molecule and a chemical bond that always lay down behind all computational modeling in quantum chemistry and of the endohedral fullerene He2@С60 in particular. For this purpose, we offer the definition of quantum chemistry as composed of three ingredients. Each of them is illustrated by its particular concept, either that of a molecule or a bond. The third, computational ingredient is tackled to resolve the bonding manifold of He2@С60E.S. Kryachko
- The thermoelectric properties of molecular nanostructures have been investigated. The mechanism of transport in these structures associated with electron tunneling has been explained. The Seebeck coefficient for such structures is found to be in good agreement with experiment. It is shown that thermoelectric effects in these nanostructures can be enhanced by changing some parameters.V. Ermakov, S.P. Kruchinin
- A mechanism of regulation of enzymatic activity has been proposed. It is alternative to allostery since it does not require the interaction between spatially separated binding sites and is of purely kinetic nature. As distinct from the classical allostery schemes in which the regulation amplitude is restricted by the degree of oligomery of the enzyme, the kinetic mechanism provides much more enhanced control possibilities by means of simply changing the relation between the times of the turnover of the enzyme and its structural relaxation. The existence of such apparent "allostery" and its physiological importance have been recently proved experimentally, see PNAS USA, 112, 11430 and 11553, Sept 15, 2015L.N. Christophorov
- Properties of a two-electron quantum dot in an external magnetic field are investigated using the variational method. The spectrum and eigenstates of a two-dimensional parabolic quantum dot are calculated with allowance for correlation effects. Such quantum dots can serve as blocks in spin electronics.S.P. Kruchinin
- Parameters of the trapping centers in the layered crystalline matrix of cadmium iodide with lead iodide nanoinclusions were calculated. Relationship of the system's properties with the type of crystalline modification of nanoinclusions was established. The processes of charge carrier migration in the heterosystem were analyzed considering orientation effects.N.V. Goloskovskaya
- We propound a computational approach, including smaller fullerenes, C20 and C28, to demonstrate that encapsulation of He2 inside the studied fullerenes exhibits an interesting quantum behavior resulting in a binding at shorter than van-der-Waals internuclear distances, and develop a computational model to interpret these He-He bonding patterns in terms of Bader's Atom-in-Molecule theory. We also conjecture computational existence of He2@C60 on a solid basis of its theoretical UV absorption spectrum and a comparison with that of C60.E.S. Kryachko
- A model of the functioning of a hysteretic enzyme is constructed with allowance for structural diffusion of the enzyme-substrate complex. It is shown that due to the nonlinear structure-function coupling (the lowering of the complex free energy due to slow structure relaxation) the enzymatic reaction rate can meet different regimes (from hyperbolic to sigmoidal/triggered saturation, substrate inhibition, etc.), subject to the solvent and structure lability characteristics.L.N. Christophorov
- Two types of nanocrystal arrangement have been found to exist in the binary layered crystal system with isomorphic inclusions: on the layer surface and along the linear structural defects of the host crystal. Within the model proposed it is shown that the excitation energy transfer to nanocrystals of the first type is realized by the electron-hole and exciton mechanisms while to those of the second type the electron-hole mechanism prevails. Calculation of the energetic characteristics involving the electron-phonon interaction allowed us to identify the 4H crystal modification of impurity nanoinclusions.N.V. Gloskovs'ka
- Superconductive properties of recently obtained MgB2 nanoparticles are studied. Within a two-level model, the two-gap superconductivity of a nanosize system is investigated. The equations for the two gaps and the condensation energy of such a system are obtained for the first time.S.P. Kruchinin
- The propensity of the fullerenes' void to form the dimers of the noble gas atoms is shown for the first time; e. g., the He-He bond length in He2@C60 is equal to 1.936 Å. To experimentally detect the aforementioned endofullerenes, we obtain, by means of vdW-corrected time-dependent density functional formalism, the UV absorption spectrum of He2@C60 which exhibits a well-defined absorption peak at ~360 nm and a broad absorption between 450 and 650 nm.E.S. Kryachko
- It is shown that the manifestations of monomeric cooperativity observed in the functioning of some enzymes (hexokinases, oxidases, transporters and others), especially in recent experiments on single molecules, can be hardly explained quantitatively or qualitatively within modified Michaelis-Menten schemes. Instead, they are readily apparent from a nonlinear sorption theory we have developed.L.N. Christophorov
- The capability of C60 to form the dimers and trimers of the rare-gas atoms, He2,3 and Ne2,3 where, for example, the former dimer features the equilibrium bond length of 1.94 Å, is studied invoking the density functional method that accounts for the van der Waals interactions. The reactivity propensity of confinement of these nano-void structures C60 is investigated by means of the global characters, such as ionization potential and electron affinity, as well as by means of the molecular electrostatic potential and the HOMO-LUMO patterns.E.S. Kryachko
- Since one of the chief concepts of molecular interactions is the concept of the molecular potential, we focuse on the class of so called spiked potentials. It is analytically demonstrated that despite the common belief that the traditional perturbation theory is not applicable to study the class of potentials combinig the harmonic oscillator with a singular potential of the type Λ/Rλ, this work aims to propose nd develop such treatment on the basis of the appropriate choice of the zero-order exactly solvable Hamiltonian H0.E.S. Kryachko
- Proceeding from stochastic trajectories obtained within the two-state reaction model of a single biomolecule functioning in a flow regime, the corresponding on-time distributions and autocorrelation functions of high accuracy are calculated. A detailed analysis of the dependence of their spectrum shape on the intensity (control parameter) of initialization of the reaction shows that these characteristics undergo distinctive qualitative changes in the bistability window. In other words, simple indicators of the possibility of molecular synergetic regimes (predicted by us earlier) in single-molecule experiments are found.L.N. Christophorov
- Revealing the mechanisms of structural regulation in biomolecular reactions meets serious difficulties in view of their hidden nature. Modern experimental and computing means are still too insufficient to simultaneously monitor the reaction course and concomitant conformational changes whose traces are deciphered from the reaction kinetics only. It is shown that the diffusion model approach we have developed is a rather general, effective and computationally friendly tool of that deciphering, producing reliable conclusions in various aspects of the functioning and structural relaxation of proteins.L.N. Christophorov
- The thermoelectrical properties of the organic molecule BDT are theoretically studied. It is shown that the mechanism of formation of these properties is rooted in the HOMO-LUMO electron tunneling. The Seebeck coefficient of this molecule is calculated in good agreement with experiment.S.P. Kruchinin
- Composite superconductive nanowires are theoretically investigated. Within the framework of the Bogolyubov-deGennes equations their spectrum and wave functions are studied. It is shown that the spectrum of such systems shows an interesting behaviour originated in their symmetry.S.P. Kruchinin
- Structural and energy characteristics of water solutions of gases are investigated by the Monte-Carlo method. The interaction between water molecules are prescribed by the Mercedes Benz model whereas that between gas and water molecules - by Lennard-Jones potentials. The gas molecule subsystem is modelled in the grand canonical ensemble. The dependence of the hydration shell properties on the admixture size is described. It is found that with the size of the admixture particles growing, the tendency of their clasterization shows up.N.V. Gloskovs'ka
- The present work investigates the relationship between the stability of multi-electron systems and the protonation. The intricacy of the protonation sites and the protonated states that are absorbed into the concept of the proton affinity is discussed, particularly addressing its range of validity. This work can also be considered as an attempt to have a look "at different angles" at one of the most important molecular processes that occur in nature and that are reflected in our mirror of the perception of nature.V.Ya. Antonchenko, E.S. Kryachko
- Тheoretical studies the thermoelectricity properties of organic molecules. Explained the mechanism of the thermoelectricity of such molecules which associated with tunneling of electrons through HOMO and LUMO levels these molecules. Investigated of the two dimensional hybrid nanostructures ferromagnetic -superconductors. Spin-orientation phase transition to study in these systems depending on temperature. We investigate the band structure of Fe-based using the first-principle method of density-functional theory .It was shown that there is scope for rising of Tc for this superconductors.S.P. Kruchinin
- It is shown that the structural response of the protein macromolecule performing a biochemical reaction manifests itself through the gamma-distribution of relaxation times which is of universal character and holds at all temperatures of the protein functioning.L.M. Christophorov
- Five 20-nanogold low-energy hollow cages are identified at the density functional level by performing a computational search on the corresponding potential energy surfaces in the different charge states. Their structures and stabilities are investigated and compared with the tetrahedral ground-state and space-filled cluster Au20(Td). Special attention is devoted to the bifunctional reactivity of the studied Au20 hollow cages: the outer, exo-reactivity and the inner, void reactivity. The latter results in endohedrality, i. e. in the existence of @-fullerenes of gold. We analyze the general features of the voids of the reported 20-nanogold fullerenes. The void reactivity of these 20-nanogold hollow cages is the key theme - it is suggested that, together with the global characteristics, such as the ionization potential and electron affinity, the molecular electrostatic potential and HOMO-LUMO patterns are actually tools that may shed a light on the general features of voids of these golden fullerenes and their capability to encage H and Li. The confinement character of the studied golden fullerenes is compared with the classical examples, C60 in particular. For the first time it is demonstrated the very existence of the stable endo-20-nanogold fullerene Li@Au20.E.S. Kryachko
- The properties of water solution 2D model system in NPT-ensemble were studied in the frames of Monte Carlo method. Dependencies of thermodynamic properties on the impurity particle size and concentration were considered. Strengthening of hydrogen bonds takes place in the vicinity of small-size impurity particles. When the particles grow in size, the structure of hydrogen bonds becomes more loosen and the particles are likely to form aggregates. Phase transition temperature under constant pressure exhibits a tendency to decrease. Obtained results and developed computational procedure can be used in the experimental data analysis on the inert gas solutions in water systems.N.V. Gloskovskaya