2,075 research outputs found
Theoretical approaches to elections defining
Theoretical approaches to elections defining develop the nature, essence and content of elections, help to determine their place and a role as one of the major national law institutions in democratic system
Dislocations in stacking and commensurate-incommensurate phase transition in bilayer graphene and hexagonal boron nitride
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.Comment: 15 pages, 9 figure
Nanotube-based scanning rotational microscope
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
confirms 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.Comment: 4 pages, 3 figure
Analysis of migration processes based on census data
The subject matter of research is the internal migration processes of the Russian population in the period from the 1960s to 2010. The research is based on the data about the territorial population flows published in the all-Union census materials of 1970, 1979, and 1989, and in the all-Russia census materials of 2002 and 2010. The basic migration flows and directions are considered. Methodologically, the analysis of migration is based on the use of end-to-end indicators enabling to assess the dynamics of migration processes over a long period. Special attention is paid to rural-urban internal migrations, the volumes, patterns and consequences of which have not been so far properly investigated or assessed. The authors offer and calculate relative indicators that have never been used to assess the processes in question. To make the census materials of the soviet and post-soviet periods comparable, the economic zoning adopted before 2000 is used, and the administrative-territorial network is unified. The authors confirm the hypothesis that from decade to decade the intensity of territorial mobility of both urban and rural population was reduced. Interregional migration flows are considered, and various tendencies and migration intensity for over four decades are de ned. The authors analyze the dynamics in the structure of migrants by the time they lived in the place of their permanent residence in various regions. The research shows that the tendencies developed at that time and persisting continue to adversely affect the territorial re-distribution of population and the regional social and economic development of the country. The research results can be used in adjusting the regional socio-economic and migration policy.The article has been prepared with the support of the Russian Humanitarian Science Foundation Project № 14–02–00525
Electron mobility on a surface of dielectric media: influence of surface level atoms
We calculate the contribution to the electron scattering rate from the
surface level atoms (SLA), proposed in [A.M. Dyugaev, P.D. Grigoriev, JETP
Lett. 78, 466 (2003)]. The inclusion of these states into account was
sufficient to explain the long-standing puzzles in the temperature dependence
of the surface tension of both He isotopes and to reach a very good agreement
between theory and experiment. We calculate the contribution from these SLA to
the surface electron scattering rate and explain some features in the
temperature dependence of the surface electron mobility. This contribution is
essential at low temperature when the He vapor concentration is
exponentially small. For an accurate calculation of the electron mobility one
also needs to consider the influence of the clamping electric field on the
surface electron wave function and the temperature dependence of the He3
chemical potential.Comment: 6 pages, 1 figur
Comparison of performance of van der Waals-corrected exchange-correlation functionals for interlayer interaction in graphene and hexagonal boron nitride
Exchange-correlation functionals with corrections for van der Waals
interactions (PBE-D2, PBE-D3, PBE-D3(BJ), PBE-TS, optPBE-vdW and vdW-DF2) are
tested for graphene and hexagonal boron nitride, both in the form of bulk and
bilayer. The characteristics of the potential energy surface, such as the
barrier to relative sliding of the layers and magnitude of corrugation, and
physically measurable properties associated with relative in-plane and
out-of-plane motion of the layers including the shear modulus and modulus for
axial compression, shear mode frequency and frequency of out-of-plane
vibrations are considered. The PBE-D3(BJ) functional gives the best results for
the stackings of hexagonal boron nitride and graphite that are known to be
ground-state from the experimental studies. However, it fails to describe the
order of metastable states of boron nitride in energy. The PBE-D3 and vdW-DF2
functionals, which reproduce this order correctly, are identified as the
optimal choice for general studies. The vdW-DF2 functional is preferred for
evaluation of the modulus for axial compression and frequency of out-of-plane
vibrations, while the PBE-D3 functional is somewhat more accurate in
calculations of the shear modulus and shear mode frequency. The best
description of the latter properties, however, is achieved also using the
vdW-DF2 functional combined with consideration of the experimental interlayer
distance. In the specific case of graphene, the PBE-D2 functional works very
well and can be further improved by adjustment of the parameters.Comment: 22 pages, 4 figue
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