"Carcass" wavefunctions in many-particle variational calculations
"Carcass" wavefunctions in many-particle variational calculations
P.P. Zakharov, N.N. Kolesnikov, V.I. Tarasov
We present a refined procedure for many-particle variational calculations. The procedure is based on the use of "carcass" trial wave-functions which reach a maximum for a definite spatial configuration of the particles. This configuration is given by a system of variational vectors. Using the example of three- and four-particle calculations we show that this procedure is capable of improving considerably the convergence of the variational calculations. Despite the more complex form of the matrix elements this procedure is, in many cases, more economical than the analogous calculations with non-carcass wavefunctions.
Show AbstractCalculation of the single and double ionization cross sections of helium by protons
Calculation of the single and double ionization cross sections of helium by protons
V.A. Disorovich, V.S. Nikolaev
The independent-electron approximation is used to calculate the single and double ionization cross sections of helium atoms by protons with energies $E$ from 0.01 to 5 MeV. The calculation is carried out for three variants of the one-electron transition probabilities to the continuum. For all energies $E$, the results of the calculation agree qualitatively with experiment, and for $E>$0.1 MeV, the calculated single ionization cross sections coincide with the experimental values. The double ionization cross sections for $E=$0.2-0.7 MeV lie higher, and for $E=$1.5-4 MeV, than the experimental values. This is apparently caused by the neglect of the shock effect on the ionization amplitude.
Show AbstractAbsorption in systems of multilayer interference light filters. Effective systems of light filters
Absorption in systems of multilayer interference light filters. Effective systems of light filters
A.Yu. Klement'eva, L.S. Kornienko, A.V. Grishkin
We study the spectral characteristics $T(\lambda)$, $A(\lambda)$, and $R(\lambda)$ of different types of multilayer interference light filters. It is shown that, at the expense of a higher complexity of light-filter system, one can obtain large values of the transmission coefficient $T_{max}$ for a given bandwidth and given physical parameters of the layers.
Show AbstractDistribution of time resources for the measurements in an experiment
Distribution of time resources for the measurements in an experiment
Yu.P. Pyut'ev, P.V. Golubtsov
In experimental investigations, one often encounters a situation where a cycle of measurements id designed under the condition that the total duration of the measurements is fixed. In this work, we develop methods which make it possible, in a number of cases, to increase considerably the accuracy of the measurements. We introduce the notion of design efficiency, which makes it possible to estimate, without finding the optimal strategy, the decrease of errors as a result of the redistribution of the time resources between measurements.
Show AbstractTheory of nonlinear optical picosecond spectrochronograph
Theory of nonlinear optical picosecond spectrochronograph
I.Yu. Pirogova, A.P. Sukhorukov
We consider the combined-frequency generation during the noncollinear interaction of very short light pulses in a nonlinear crystal. It is shown that it is possible to obtain information about the duration and spectrum of the optical pulse by measuring the space-angular radiation pattern of the combined frequency in two mutually perpendicular transverse direction. We present results of calculation of the dispersion of direction of the doubling synchronism for the crystals LiIO$_3$, KDP, and ADP.
Show AbstractTheory of scattering of two quantum particles from a third heavy particle
Theory of scattering of two quantum particles from a third heavy particle
A.M. Popova, Yu.Y. Popov
We study the solution of Faddeev equation for the three-body problem in the limit when mass of one of the particles tends to infinity. It is shown that the solution does not have a continuous transition in this limit, and the required scattering amplitude for the two light particles from an infinitely heavy particle must be obtained by reconstructing the Faddeev equations, which reduces them to the equations of a two-body problem in a field.
Show AbstractExcitation of autoionization states of atoms by electron impact using the Born and distorted-waves approximation
Excitation of autoionization states of atoms by electron impact using the Born and distorted-waves approximation
A.N. Grum-Grzhimailo, A.I. Magunov
Using the Born and distorted-waves approximations, we develop a method for the description of inelastic scattering of intermediate-energy electrons from atoms, with allowance for the excitation of autoionization states. The excitation of the state $^4d-^1 5p^1 P$ of a cadmium atom is used to discuss some features of the resonant ionization which are due to the distortions of the incident and scattered waves in comparison with the plane-wave Born approximation.
Show AbstractAmplitude dependence of internal friction in cesium iodide crystals
Amplitude dependence of internal friction in cesium iodide crystals
G.Z. Kurbanov, E.K. Naimi, N.A. Tyapunina
We study the dependence of internal friction on the amplitude of ultrasound oscillation in the monocrystals of cesium iodide, which were plastically deformed during preparation and mounting; we also studied aged sample. In samples oriented along [110], we observe an amplitude dependence of the internal friction. It is shown that the internal friction is caused by the dislocation mechanism of ultrasound absorption. We estimate the change of the effective length of dislocation loops during aging.
Show AbstractRecoil effects and quantum corrections in the semiclassical theory of synchrotron radiation
Recoil effects and quantum corrections in the semiclassical theory of synchrotron radiation
I.M. Ternov, V.A. Bordovitsyn
In a linear approximation with respect to the spin and quadrativ with respect to the recoil parameter, we obtain quantum corrections to the power of synchrotron radiation of an electron. The spin correction is equal to $\xi \zeta$, and the first and second (boson) corrections are $(55\sqrt{3/24})\xi$ and $(56/3)\xi ^2$.
Show AbstractTopological invariants in the generalized theories of gravitation
Topological invariants in the generalized theories of gravitation
V.V. Trefilov, N.F. Nelipa
For spaces with affine connectivity, we obtain a criterion for the existence of a generalized Euler's class and the Lanczos-Bach formula. It is shown that this criterion is fulfilled in the spaces of Weyl and Einstein-Cartan.
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