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1.
Superintegrability on N-dimensional spaces of constant curvature from so(N + 1) and its contractions
The Lie—Poisson algebra so(N + 1) and some of its contractions are used to construct a family of superintegrable Hamiltonians on the N-dimensional spherical, Euclidean, hyperbolic, Minkowskian, and (anti-)de Sitter spaces. We firstly present a Hamiltonian
which is a superposition of an arbitrary central potential with N arbitrary centrifugal terms. Such a system is quasi-maximally superintegrable since this is endowed with 2N — 3 functionally independent constants of motion (plus the Hamiltonian). Secondly, we identify two maximally superintegrable
Hamiltonians by choosing a specific central potential and finding at the same time the remaining integral. The former is the
generalization of the Smorodinsky—Winternitz system to the above six spaces, while the latter is a generalization of the Kepler—Coulomb
potential, for which the Laplace—Runge—Lenz N vector is also given. All the systems and constants of motion are explicitly expressed in a unified form in terms of ambient
and polar coordinates as they are parametrized by two contraction parameters (curvature and signature of the metric).
The text was submitted by the authors in English. 相似文献
2.
K L Sebastian 《Pramana》1978,10(4):341-348
As an improvement over the Hartree-Fock approximation, we investigate a Green’s Function method—theΣ perturbation method—for molecular calculations. The method is applied to hydrogen molecule and to theπ-electron system of ethylene under PPP approximation. When the algebraic approximation is used, the energy obtained is better
than that of the HF approach, but is not as good as that of the configuration-interaction method. The main advantage of this
procedure is that it is devoid of the most serious defect of HF method, viz. incorrect dissociation limits. 相似文献
3.
V. V. Putrolainen P. P. Boriskov A. A. Velichko A. L. Pergament N. A. Kuldin 《Technical Physics》2010,55(2):247-250
Experimental data for the effect of memory electrical switching in a metal—oxide—metal structure based on hydrated vanadium
dioxide obtained by the method of anodic—cathodic polarization are discussed. A model that assumes the key role of the ion
current in the switching mechanism is suggested. This model makes it possible to determine the critical parameters of the
material (the concentration and mobility of impurity ions) that influence the origination of the effect. The field dependence
of the ion mobility derived by simulating the switching effect is explained through the hopping transfer mechanism in terms
of the percolation theory. 相似文献
4.
R.S. Berry A. Fernandez K. Kostov 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,16(1):47-50
The relaxation dynamics of clusters can be interpreted in terms of the topographies of their potential surfaces. Systems with
short-range potentials have sawtooth-like potential surfaces with small drops in energy from one local minimum to the next
and few-body motions as the clusters move from one minimum to another; such systems readily take on amorphous structures.
These are called “glass-formers". Systems with long-range forces have potentials whose topographies are like rough staircases,
with some large drops in energy from one minimum to the next; their well-to-well passages involve very collective motions
and such systems are excellent structure-seekers. They find their way to well-ordered, highly selective structures under almost
all circumstances. These characteristics generalize to describe the potential surfaces and folding behavior of polypeptides
and proteins. The forces are effective long-range forces due to the polymer chain. Staircase topographies emerge both from direct sampling of potential surfaces
and from the inversion of the kinetics generated by a much more aaabstract topological model, from which folding pathways
can be inferred.
Received 4 December 2000 相似文献
5.
Li Tszen’ Fen’ G. E. Remnev M. S. Saltymakov V. I. Gusel’nikov V. A. Makeev I. V. Ivonin E. P. Naiden V. I. Yurchenko 《Russian Physics Journal》2007,50(1):66-70
The results of examination of the GaAs-target erosion under irradiation by a high-power pulsed ion beam are reported. In the experiments, use was made of a high-power
pulsed ion source with the following parameters: ion energy — 250 keV, target current density — 350 A/cm2, pulse duration — 80 ns, target energy density — up to 7 J/cm2. The target erosion coefficient and its dependence on the number of successive pulses are measured. It is found that the
surface roughness parameter is increased with the number of successive beam pulses. A regular structure of surface relief
is observed to form in the case where the number of pulses > 20–40.
__________
Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 1, pp. 66–70, January, 2007. 相似文献
6.
Anton A. Akhsakhalyan Aram D. Akhsakhlyan Alexander I. Kharitonov Eugenie B. Kluenkov Vladimir A. Murav’ev Nikolay N. Salashchenko 《Central European Journal of Physics》2005,3(2):163-177
This paper is an overview of the research activities carried out in the past five years at the Institute for Physics of Microstructures
RAS and “X-ray” Company towards the manufacture of multilayer mirror systems capable of forming X-ray beams in the subnanometer
range of wavelengths. The systems fabrication technology is presented, including techniques for producing supersmooth surfaces
of specified shape, methods of graded multilayer structure deposition on such surfaces, and the principles of designing optimal
mirror parameters. The characteristics of a quadrelliptical reflector—a novel high light-gathering power four-corner focusing
system—are reported. 相似文献
7.
V. V. Val’kov S. V. Aksenov 《Bulletin of the Russian Academy of Sciences: Physics》2010,74(5):731-733
The influence of inelastic spin-dependent effects on the transport of a spin-polarized electron through model nanostructures
of two-, four- and six-spi n clusters was investigated. It was shown that the spin—flop processes induced by the s-d(f)-exchange interaction of an electron and a nanocluster lead to changes in the potential profile and to qualitative changes
in the transport characteristics’ energy dependence. 相似文献
8.
Yu. V. Tertyshnaya L. S. Shibryaeva A. A. Popov 《Russian Journal of Physical Chemistry B, Focus on Physics》2012,6(1):38-41
The relationship between the structure and the kinetics of the thermal oxidation of the poly(3-hydroxybutyrate) — ethylene
propylene rubber and polyethylene — poly(3-hydroxybutyrate) systems is studied. For the first system containing 30–50 wt %
poly(3-hydroxybutyrate), phase inversion is observed, which affects its reactivity. For the compositions with polyethylene,
two stages of oxidation manifest themselves: before and after poly(3-hydroxybutyrate) degradation. 相似文献
9.
We give the first explicit construction of the quadratic algebra for a 3D quantum superintegrable system with nondegenerate
(4-parameter) potential together with realizations of irreducible representations of the quadratic algebra in terms of differential—differential
or differential—difference and difference—difference operators in two variables. The example is the singular isotropic oscillator.
We point out that the quantum models arise naturally from models of the Poisson algebras for the corresponding classical superintegrable
system. These techniques extend to quadratic algebras for superintegrable systems in n dimensions and are closely related to Hecke algebras and multivariable orthogonal polynomials. 相似文献
10.
Beatrix C. Hiesmayr Antonio Di Domenico Catalina Curceanu Andreas Gabriel Marcus Huber Jan-Åke Larsson Pawel Moskal 《The European Physical Journal C - Particles and Fields》2012,72(1):1856
Entanglement and its consequences—in particular the violation of Bell inequalities, which defies our concepts of realism and
locality—have been proven to play key roles in Nature by many experiments for various quantum systems. Entanglement can also
be found in systems not consisting of ordinary matter and light, i.e. in massive meson–antimeson systems. Bell inequalities
have been discussed for these systems, but up to date no direct experimental test to conclusively exclude local realism was
found. This mainly stems from the fact that one only has access to a restricted class of observables and that these systems
are also decaying. In this Letter we put forward a Bell inequality for unstable systems which can be tested at accelerator
facilities with current technology. Herewith, the long awaited proof that such systems at different energy scales can reveal
the sophisticated “dynamical” nonlocal feature of Nature in a direct experiment gets feasible. Moreover, the role of entanglement and CP\mathcal{CP} violation, an asymmetry between matter and antimatter, is explored, a special feature offered only by these meson–antimeson
systems. 相似文献
11.
Relativistic constraint mechanics yields consistent systems of coupled Dirac equations for pairs of spinning particles. We
explicitly connect these equations to the Bethe-Salpeter equation of quantum field theory and to the interactions of classical
Fokker-Tetrode dynamics (and hence to classical relativistic field theory) to obtain versions of these equations governed
by systems of (possibly noncoulombic) relativistic potentials whose detailed structures contain important relativistic effects
like correct Darwin interactions. We recast the defining pair of Dirac equations in a number of equivalent but important forms—“external
potential,” Sazdjian, hyperbolic, and Breit— and examine their interconnection. Since the potentials in these equations are
no more singular than — 1/4r2 we are able to solve appropriate versions of them nonperturbatively for the qˉq system to obtain a very good fit to the entire
meson spectrum and for the e
+
e
−
system to calculate the positronium spectrum of QED correct through order α
4
. 相似文献
12.
H. Krompholz L. Michel K. H. Schönbach Heinz Fischer 《Applied Physics A: Materials Science & Processing》1977,13(1):29-35
The neutron energy spectrum (4 Torr deuterium) was determined from 30 m flight histograms.—An average energy of approximately
100±20 keV of the neutron producing deuterons within an assumed cone angle of approximately 40 degrees along thez-axis was calculated by means of the target beam model.—Shadow bar techniques reveal that only 10% of the neutrons are produced
in the ≈1 cm long focus.—Experimental time of flight analysis confirms that the ion spectrum extends from less than 70 to
greater than 400 keV. The electron spectrum in 8 Torr hydrogen follows a ≈3 keV Boltzmann distribution, but demonstrates the
presence of nonthermal >100 keV electrons. 相似文献
13.
Wagendristel A. Tschegg E. Semerad E. Bangert H. 《Applied Physics A: Materials Science & Processing》1976,10(3):237-243
Computer simulation of superimposed lattice, grain boundary and surface diffusion, characteristic for polycrystalline thin
film diffusion systems, was performed by way of discretisation of the nonlinear diffusion law. In order to give a vivid impression
how such a complex process takes place under some typical conditions we have chosen pseudo three-dimensional computer plots
of the spacial distribution of the concentration instead of the commonly used iso-concentration diagrams. The following cases
are considered:
相似文献
a) | Polycristal — single crystal couple with highly diffusive grain boundaries and surfaces, grain boundaries and interface, grain boundaries, surfaces and interface. |
b) | Polycrystal — polycrystal couple with different displaced grain boundaries as well as different diffusivity ratios for the bulk and the highly conducting regions. |
14.
Alexios Papadimitratos Aram Amassian Aravind S. Killampalli Jared L. Mack George G. Malliaras James R. Engstrom 《Applied Physics A: Materials Science & Processing》2009,95(1):29-35
Top-contact organic thin-film transistors (OTFTs) of pentacene have been fabricated on bare SiO2 and SiO2 modified with hexamethyldisilazane (HMDS) and octadecyltrichlorosilane (OTS). The pentacene films were deposited from a supersonic
molecular beam source with kinetic energy of incident molecules ranging from 1.5 to 6.7 eV. The field-effect mobility of OTFTs
was found to increase systematically with increasing kinetic energy of the molecular beam. The improvements are more important
on HMDS- and OTS-treated surfaces than on bare SiO2. Tapping mode atomic force microscopy images reveal that pentacene thin films deposited at high kinetic energy form with
significantly larger grains—independent of surface treatment—than films deposited using low-energy beams. 相似文献
15.
D. P. Sheehan 《Foundations of Physics》2007,37(12):1774-1797
Two categories of life are currently recognized—chemosynthetic and photosynthetic—indicating their principal free energy resource
as either chemicals or electromagnetic radiation. Building on recent developments in thermodynamics, we posit a third category
of life—thermosynthetic life (TL)—which relies on environmental heat rather than traditional free energy sources. Since thermal energy is more abundant
than chemicals or light in many settings, thermosynthesis offers compelling evolutionary possibilities for new life forms.
Based on variants of standard cellular machinery, a physical model is proposed for the conversion of thermal energy into biochemical
work. Conditions favorable to thermosynthetic life and prospects for its discovery are assessed. Terrestrially, deep-subsurface
unicellular anaerobic superthermophiles are deduced to be likely TL candidates. 相似文献
16.
Two-dimensional microclusters made up of particles repelled by the dipole law and confined by an external quadratic potential
are considered. The model describes a number of physical systems, in particular, electrons in semiconductor structures near
a metallic electrode, indirect excitons in coupled semiconductor dots etc. Two competing types of particle ordering in clusters
have been revealed: formation of a triangular lattice and of a shell structure. Equilibrium configurations of clusters with
N=1–40 particles are calculated. Temperature dependences of the structure, potential energy, and mean-square radial and angular
displacements are studied. These characteristics are used to investigate cluster melting. Melting occurs in one or two stages,
depending on N. Melting of a two-shell microcluster takes place in two stages: at low temperatures—from the frozen phase to a state with
rotationally reoriented “crystalline” shells with respect to one another, followed by a transition involving breakdown of
radial order. Melting in a cluster made up of a larger number of shells occurs in one stage. This is due to the fact that
the potential barrier to intershell rotation is substantially lower than that to particle jumping from one shell to another
for small N, and of the same order of magnitude for large N. A method is proposed for predicting the character of melting in shell clusters by comparing the potential barriers for shell
rotation and intershell particle jumping.
Fiz. Tverd. Tela (St. Petersburg) 40, 1379–1386 (July 1998) 相似文献
17.
G. V. Golubkov M. G. Golubkov 《Russian Journal of Physical Chemistry B, Focus on Physics》2010,4(2):185-197
The special features of the behavior of the potential energy surfaces of the system comprising a highly excited A** atom and
a neutral B atom with a filled electronic shell were thoroughly analyzed. This was done using the integral variant of theory
combined with the generalized finite radius potential method correctly describing the scattering of a weakly bound electron
by the B atom. The method allows P scattering to be taken into account. This scattering causes the additional splitting of potential energy surfaces into separate
groups of interacting terms classified according to the projection m of the electron angular momentum l onto the quasimolecular axis. Calculations of the nl(2s + 1Λ) state potential curves of the Na** + He quasi-molecule (n, l, and Λ are the principal quantum number, angular momentum, and its projection onto the molecular axis, and s is the spin of the system) were performed. The calculation results were compared to those obtained by other authors. 相似文献
18.
S. G. Ovchinnikov 《JETP Letters》1996,64(1):25-31
The Fermi and Bose quasiparticle spectrum in copper oxides is studied in a many-band p-d model taking account of the strong electronic correlations. It is shown that hole-doped systems possess a Bose mode — a spin
exciton — which is associated with the singlet-triplet excitation of the two-hole ground-state term of CuO4 clusters. Intercluster hopping leads to fermion-boson interaction with a spin exciton as the intermediate boson. Such a mechanism
does not exist for n-type systems.
Pis'ma Zh. éksp. Teor. Fiz. 64, No. 1, 23–28 (10 July 1996) 相似文献
19.
A precise solution of the classical energy functional E(N, η, χ; β) minimum problem with respect to deformation parameter β is obtained for the simplified Casten version of the standard interacting boson model (IBM-1) Hamiltonian. The first-order
phase transition lines as well as the critical points of X(5), -X(5), and E(5) symmetries are considered. The dynamical criteria of quantum chaos—the basis state fragmentation width and the wave function
entropy—are studied for the (η, χ) parameter space of the extended Casten triangle, and the possible relationships between these criteria and phase transition
lines are discussed.
The text was submitted by the authors in English. 相似文献
20.
J. Proskurins A. Andrejevs T. Krasta L. Neiburgs J. Tambergs’ 《Bulletin of the Russian Academy of Sciences: Physics》2007,71(6):894-900
In this study of the classical energy limit of an interacting boson model with three-body interactions, two variants are considered:
the inclusion of cubic d-boson interaction terms and the inclusion of three-body O(6) symmetric quadrupole operator terms. The solutions of the corresponding energy minimum condition equations are used for
analysis of the triaxiality of the nuclear shape in the first case and for analysis of spherical—prolate—oblate shape phase
transitions in the second case.
The text was submitted by the authors in English. 相似文献