Moscow, Russia
Moscow, Russia

Kintech Lab is a software company headquartered in the Russia. It provides computer simulation software in the areas of combustion, energy sources, photonics, microelectronics, nanotechnology. Also Kintech Lab is the R & D company performing scientific research projects in the above-mentioned areas. Kintech Lab was established in 1998 by a group of scientists from RSC Kurchatov Institute. Wikipedia.

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Lebedeva I.V.,University of the Basque Country | Knizhnik A.A.,Kintech Lab | Popov A.M.,Russian Academy of Sciences
Physica E: Low-Dimensional Systems and Nanostructures | Year: 2017

Incomplete stacking dislocations are predicted to form at edges of the shorter upper layer in two-dimensional hexagonal bilayers upon stretching the longer bottom layer. A concept of the edge Burgers vector is introduced to describe such dislocations by analogy with the Burgers vector of standard bulk dislocations. Analytical solutions for the structure and energy of edge stacking dislocations in bilayer graphene are obtained depending on the magnitude of elongation and angles between the edge Burgers vector, direction of elongation and edge. The barrier for penetration of stacking dislocations inside the bilayer is estimated. The possibilities to measure the barrier to relative motion of graphene layers and strain of graphene on a substrate by observation of edge stacking dislocations are discussed. © 2017 Elsevier B.V.

Lebedeva I.V.,University of the Basque Country | Lebedev A.V.,Kintech Lab | Popov A.M.,Russian Academy of Sciences | Knizhnik A.A.,RAS Research Center Kurchatov Institute
Physical Review B - Condensed Matter and Materials Physics | Year: 2016

Dislocations corresponding to a change of stacking in two-dimensional hexagonal bilayers, graphene and boron nitride, and associated with boundaries between commensurate domains are investigated using the two-chain Frenkel-Kontorova model on top of ab initio calculations. Structural transformations of bilayers in which the bottom layer is stretched and the upper one is left to relax freely are considered for gradually increased elongation of the bottom layer. Formation energies of dislocations, dislocation width, and orientation of the boundary between commensurate domains are analyzed depending on the magnitude and direction of elongation. The second-order phase transition from the commensurate phase to the incommensurate one with multiple dislocations is predicted to take place at some critical elongation. The order parameter for this transition corresponds to the density of dislocations, which grows continuously upon increasing the elongation of the bottom layer above the critical value. In graphene and metastable boron nitride with the layers aligned in the same direction, where elementary dislocations are partial, this transition, however, is preceded by formation of the first dislocation at the elongation smaller than the critical one. The phase diagrams including this intermediate state are plotted in coordinates of the magnitude and direction of elongation of the bottom layer. © 2016 American Physical Society.

Popov A.M.,Russian Academy of Sciences | Lebedeva I.V.,Kintech Lab | Knizhnik A.A.,RAS Research Center Kurchatov Institute
Applied Physics Letters | Year: 2012

A scheme of the scanning rotational microscope is designed. This scheme is based on using carbon nanotubes simultaneously as a probe tip and as a bolt/nut pair which converts translational displacements of two piezo actuators into pure rotation of the probe tip. First-principles calculations of the interaction energy between movable and rotational parts of the microscope confirm the capability for its operation. The scanning rotational microscope with a chemically functionalized nanotube-based tip can be used to study how the interaction between individual molecules or a molecule and a surface depends on their relative orientation. © 2012 American Institute of Physics.

Popov A.M.,Russian Academy of Sciences | Lebedeva I.V.,Kintech Lab | Knizhnik A.A.,RAS Research Center Kurchatov Institute | Lozovik Y.E.,Moscow Institute of Physics and Technology | Potapkin B.V.,RAS Research Center Kurchatov Institute
Journal of Physical Chemistry C | Year: 2013

The possibility to control the commensurability and distance between graphene layers separated by a dielectric spacer is considered by the example of a heterostructure consisting of double-layer graphene separated by atomic layers of argon. Van der Waals-corrected density functional theory (DFT-D) is applied to study structural, energetic, and tribological characteristics of this heterostructure. It is found that, in the ground state, monolayer and bilayer argon spacers are incommensurate with the graphene layers, whereas sub-monolayer argon spacers which are commensurate with the graphene layers can exist only as metastable states. The calculations show that this incommensurability provides negligibly small static friction for relative motion of argon-separated graphene layers; therefore, such a heterostructure holds great promise for use in nanoelectromechanical systems. A scheme and operational principles of the nanorelay based on the revealed tribological properties of the heterostructure are proposed. © 2013 American Chemical Society.

Kretov M.K.,Moscow State University | Iskandarova I.M.,Kintech Lab | Potapkin B.V.,RAS Research Center Kurchatov Institute | Scherbinin A.V.,Moscow State University | And 2 more authors.
Journal of Luminescence | Year: 2012

A sequential, fully first-principle theoretical study of the Mn 2+ green emission bands in the Zn 2SiO 4:Mn 2+ phosphor is presented for the first time. A combined approach is developed based on the modern periodic density-functional theory and cluster ab initio wave-function-based electronic structure methods, the linear response theory for lattice phonons, and generating function formalism of vibronic spectra within the displaced multi-mode harmonic oscillator model. We obtain fairly good agreement between the calculated low- and high-temperature emission band positions, widths, zero-phonon lines and phonon wings and the available experimental emission studies, with special emphasis on Mn 2+ distribution over two non-equivalent Zn 2+ sites in the Zn 2SiO 4 material. An interpretation for vibronic structure observed in the low-temperature emission spectrum of this phosphor is suggested based on the present first-principle study. © 2012 Elsevier B.V. All rights reserved.

Deinega A.,Northwestern University | Belousov S.,RAS Research Center Kurchatov Institute | Valuev I.,Kintech Lab
Physical Review E - Statistical, Nonlinear, and Soft Matter Physics | Year: 2013

Optical properties of periodic structures can be calculated using the transfer-matrix approach, which establishes a relation between amplitudes of the wave incident on a structure with transmitted or reflected waves. The transfer matrix can be used to obtain transmittance and reflectance spectra of finite periodic structures as well as eigenmodes of infinite structures. Traditionally, calculation of the transfer matrix is performed in the frequency domain and involves linear algebra. In this work, we present a technique for calculation of the transfer matrix using the finite-difference time-domain (FDTD) method and show the way of its implementation in FDTD code. To illustrate the performance of our technique we calculate the transmittance spectra for opal photonic crystal slabs consisting of multiple layers of spherical scatterers. Our technique can be used for photonic band structure calculations. It can also be combined with existing FDTD methods for the analysis of periodic structures at an oblique incidence, as well as for modeling point sources in a periodic environment. © 2013 American Physical Society.

Lebedeva I.V.,Kintech Lab | Knizhnik A.A.,RAS Research Center Kurchatov Institute | Popov A.M.,Russian Academy of Sciences | Potapkin B.V.,RAS Research Center Kurchatov Institute
Journal of Physical Chemistry C | Year: 2012

Transformation of graphene flakes to fullerenes assisted by Ni clusters is investigated using molecular dynamics simulations. The bond-order potential for Ni-C systems is developed. The potential reproduces the experimental and first-principles data on the physical properties of pure Ni as well as on relative energies of carbon species on Ni surfaces and in Ni bulk. The potential is applied for molecular dynamics simulations of the transformation of graphene flakes consisting of 50-400 atoms with and without Ni clusters attached. Free fullerenes, fullerenes with Ni clusters attached from outside, and fullerenes encapsulating Ni clusters (Ni endofullerenes) are observed to form in the presence of Ni clusters consisting of 5-80 atoms. Moreover, a new type of heterofullerenes with a patch made of a Ni cluster is found to form as an intermediate structure during the transformation. The Ni clusters are shown to reduce the activation energy for the graphene-fullerene transformation from 4.0 eV to 1.5-1.9 eV, providing the decrease of the minimal temperature at which such a transformation can be observed experimentally from about 1400 K for free graphene flakes to about 700-800 K. While the transformation of free graphene flakes is found to occur through formation of chains of two-coordinated carbon atoms at the flake edges, the mechanism of the Ni-assisted graphene-fullerene transformation is revealed to be based on the transfer of carbon atoms from the graphene flake to the Ni cluster and back. The way of controlled synthesis of endofullerenes with a transition metal cluster inside and heterofullerenes with a transition metal patch is also proposed. © 2012 American Chemical Society.

Zalyubovskiy S.J.,General Electric | Bogdanova M.,Kintech Lab | Deinega A.,Kintech Lab | Lozovik Y.,Kintech Lab | And 4 more authors.
Journal of the Optical Society of America A: Optics and Image Science, and Vision | Year: 2012

In this paper, the theoretical sensitivity limit of the localized surface plasmon resonance (LSPR) to the surrounding dielectric environment is discussed. The presented theoretical analysis of the LSPR phenomenon is based on perturbation theory. Derived results can be further simplified assuming quasistatic limit. The developed theory shows that LSPR has a detection capability limit independent of the particle shape or arrangement. For a given structure, sensitivity is directly proportional to the resonance wavelength and depends on the fraction of the electromagnetic energy confined within the sensing volume. This fraction is always less than unity; therefore, one should not expect to find an optimized nanofeature geometry with a dramatic increase in sensitivity at a given wavelength. All theoretical results are supported by finite-difference time-domain calculations for gold nanoparticles of different geometries (rings, split rings, paired rings, and ring sandwiches). Numerical sensitivity calculations based on the shift of the extinction peak are in good agreement with values estimated by perturbation theory. Numerical analysis shows that, for thin (?10 nm) analyte layers, sensitivity of the LSPR is comparable with a traditional surface plasmon resonance sensor and LSPR has the potential to be significantly less sensitive to temperature fluctuations. © 2012 Optical Society of America.

Krasikov D.,Kintech Lab | Knizhnik A.,Kintech Lab | Potapkin B.,Kintech Lab | Selezneva S.,General Electric | Sommerer T.,General Electric
Thin Solid Films | Year: 2013

The maximum voltage of CdTe solar cells is limited by low majority carrier concentration and doping difficulty. Copper that enters from the back contact can form both donors and acceptors in CdTe. It is empirically known that the free carrier concentration is several orders lower than the total Cu concentration. Simplified thermodynamic models of defect compensation after Cu introduction can be found in literature. We present a first-principles-based analysis of kinetics of defect formation upon Cu introduction, and show that Cui is mobile at room temperature. Calculations of properties of Cui-VCd and Cui-CuCd complexes show that the neutral Cui-CuCd complex is mobile at elevated temperatures, while formation of the VCd-Cui complex is unlikely because it transforms into the CuCd defect. © 2012 Elsevier B.V.

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