The effect of temperature on the nonlinear dynamics of charge in a semiconductor superlattice in the presence of a magnetic field

The space-time dynamics of electron domains in a semiconductor superlattice is studied in a tilted magnetic field with regard to the effect of temperature. It is shown that an increase in temperature substantially changes the space-time dynamics of the system. This leads to a decrease in the frequency and amplitude of oscillations of a current flowing through the semiconductor superlattice. The quenching of oscillations is observed, which is attributed to the change in the drift velocity as a function of electric-field strength under the variation of temperature.     

Relaxation of excited molecules in a medium with memory at short and long times

Two qualitatively different approaches to the dynamics of vibrational wave packets in the presence of medium-induced relaxation, with taking into account relaxation memory effects and without taking them into account (Makovian approximation) were compared for a molecular system with one vibrational degree of freedom (the Morse oscillator) in a medium. The time evolution of the populations of levels, mean system energy, and response of “pumping-probing” experiments were calculated. It was found that, as distinct from the Markovian approximation, the approach including memory effects can predict the evolution of a molecular system satisfying the detailed equilibrium principle. The two approaches specified also predict the existence of a qualitative difference of phase characteristics in the behavior of the system at short times.     

Dynamic spin susceptibility in the Hubbard model

The dynamic spin susceptibility in the Hubbard model is calculated on the basis of the new diagram technique developed for systems with strong correlation. In the leading-order approximation, the singlesite interaction is allowed and electron hopping is taken into account using the evolution operator. The second order of perturbation theory is considered and the sum of 1PI two-particle single-site diagrams of the ladder type is calculated. The equations for calculating the static susceptibility and the spin wave spectrum are obtained. Translated from Teoreticheskaya i Matematicheskaya Fizika, Vol. 113, No. 1, pp. 124–138, October, 1997.     

Electron-phonon system with strong electronic correlations

The properties of the Hubbard-Holstein model for an electron-phonon system with strong electron correlations are investigated on the basis of a new diagram technique. The equations of the main dynamical quantities and optical dispersionless phonons are established. The problem of excluding partially or completely the phonon's coordinates and the corresponding renormalization of the physical parameters of the theory is discussed.Published in Teoreticheskaya i Matematicheskaya Fizika, Vol. 103, No. 1, pp. 138–160, April, 1995.     

Relative kinetics of the telomerization of 1-hexene by diethyl phosphite

Conclusions According to relative kinetic data on the telomerization of 1-hexene by diethyl phosphite, a system based on Mn₂(CO)₁₀ effectively activates the transfer of hydrogen at the chain transfer stage.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 10, pp. 2389–2392, October, 1988.     

Luminescence of excitons in slightly asymmetric double quantum wells

We report the first studies of exciton luminescence spectra from asymmetric double quantum wells (DQWs) of very similar width. The DQWs were of GaAs/AlGaAs and the differences in widths of the coupled wells were one or two monolayers. The coupled direct and indirect exciton states anticross with a resonance splitting of 1.33 meV. An additional luminescence line appearing at low temperatures is identified as a localized indirect exciton. Fiz. Tverd. Tela (St. Petersburg) 39, 735–739 (April 1997)     

New universality type in chaotic synchronization of dynamic systems

A quite universal mechanism of establishing chaotic synchronization regime in coupled dynamic systems is found. It is shown that the synchronous regime arises due to the phase coupling between the Fourier-spectrum components of the interacting chaotic oscillators.     

Exact solutions of the d'Alembert and Liouville equations in the pseudo-Euclidean space R2, 2. II

Invariants of the maximal rank-3 and rank-4 subalgebras of the Poincaré algebras AP(2,2), which is the maximal invariance algebra of the d'Alembert equation u+u^k=0,k=1, and the Liouville equation u+ expu=0 are constructed. The reduction of the given equations with respect to the maximal rank-3 subalgebra is carried out and some exact solutions of these equations are found.Translated from Ukrainskii Matematicheskii Zhurnal, Vol. 42, No. 9, pp. 1237–1244, September, 1990.