Remarks on strongly correlated disordered cpa alloys

Strongly correlated disordered metallic alloys are discussed, within Roth's linerization method. We show that the inclusion of the complete Roth's band shift introduce a correlation-induced off-diagonal disorder, which may be treated within the extended CPA approach.     

Irreversibility in strongly coupled systems

A Boltzmann H-functional is derived in the so called physical representation introduced by Prigogine et al. It is proved that at equilibrium it contains the potential contributions to the specific entropy of the moderately dense gas. We shall discuss its validity in the linear domain of irreversible processes.     

Remarks on potential spaces and Besov spaces in a Lipschitz domain and on Whitney arrays on its boundary

In this note, we propose to remove some small gaps in the theory of potential spaces H _p ^s (Ω) and Besov spaces B _p ^s (Ω), 1 < p < ∞, s ∈ ℝ, for a bounded Lipschitz domain Ω ⊂ ℝ ⁿ , n ⩾ 2. Namely, we discuss 1) the unified definitions of these spaces with s of any sign, the unified duality theorems and interpolation relations, 2) the possibility of constructing a function in these spaces with given array of traces of its derivatives on the boundary. To the memory of Leonid Romanovich Volevich The work was partially supported by the RFBR grant no. 07-01-00287.     

Bose condensation in strongly monideal systems

The possibility of the formation of a condensate with a finite absolute value of the momentum k₀ in a strongly nonideal Bose system is considered. Such a condensate comes into existence when the one-particle spectrum of a normal system touches zero in the point k₀ ≠ 0. The form of a correlation function below the condensation point shows the appearance of a long-range order, but not the infinite long-range one. In the case of liquid ⁴He estimates show that $\text{k}{}_0\text{? 1}\text{A}\text{?}{}^{\mathrm{?1}}$, and at the temperature T>₀ ～ 1 K this unusual condensate with a finite magnitude of the momentum turns into the conventional Bose-Einstein condensate with the zero momentum. The properties of correlation functions in the spaces of different dimensions are discussed.     

Disorder screening in strongly correlated systems

Electron-electron interactions generally reduce the low temperature resistivity due to the screening of the impurity potential by the electron gas. In the weak-coupling limit, the magnitude of this screening effect is determined by the thermodynamic compressibility which is proportional to the inverse screening length. We show that when strong correlations are present, although the compressibility is reduced, the screening effect is nevertheless strongly enhanced. This phenomenon is traced to the same nonperturbative Kondo-like processes that lead to strong mass enhancements, but which are absent in weak-coupling approaches. We predict metallicity to be strongly stabilized in an intermediate regime where the interactions and the disorder are of comparable magnitude.     

Apparent electron-phonon interaction in strongly correlated systems

We study the interaction of electrons with phonons in strongly correlated solids, having high-T(c) cuprates in mind. Using sum rules, we show that the apparent strength of this interaction strongly depends on the property studied. If the solid has a small fraction (doping) delta of charge carriers, the influence of the interaction on the phonon self-energy is reduced by a factor delta, while there is no corresponding reduction of the coupling seen in the electron self-energy. This supports the interpretation of recent photoemission experiments, assuming a strong coupling to phonons.     

Charge instabilities in strongly correlated bilayer systems

We investigate the charge-instabilities of the Hubbard-Holstein model with two coupled layers. In this system the scattering processes naturally separate into contributions which are either symmetric or antisymmetric combinations with respect to exchange of the layers. It turns out that the short-range strong correlations suppress finite wave-vector nesting instabilities for both symmetries but favor the occurrence of phase separation in the symmetric channel. Inclusion of a sizeable long-range Coulomb (LRC) interaction frustrates the q=0 instabilities and supports the formation of incommensurate charge-density waves (CDW). Upon reducing doping from half-filling and for small electron-phonon coupling g the CDW instability first occurs in the antisymmetric channel but both instability lines merge with increasing g. While LRC forces always suppress the phase separation instability in the symmetric channel, the CDW period in the antisymmetric sector tends to infinity ( ) for sufficiently small Coulomb interaction. This feature allows for the possibility of singular scattering over the whole Fermi surface. We discuss possible implications of our results for the bilayer high-T _c cuprates.Received: 21 July 2003, Published online: 2 October 2003PACS: 71.27.+a Strongly correlated electron systems; heavy fermions - 74.72.-h Cuprate superconductors (high-T _c and insulating parent compounds) - 74.25.Kc Phonons     

Lipschitz quasistability of impulsive systems of differential equations

A suitable comparison lemma is used to obtain sufficient conditions for uniform Lipschitz quasistability of an arbitrary solution of an impulsive system of differential equations with unfixed moments of impulse effect. The results are applied to finding conditions for uniform Lipschitz quasistability for linear impulsive systems with unfixed moments of impulse effect.     

Lipschitz stability of impulsive systems of differential equations

Notions ofLipschitz stability of the zero solution of impulsive systems of differential equations with fixed moments of impulse effect are introduced. Sufficient conditions for various types of uniform Lipschitz stability are obtained and the relations between these notions are investigated. The results obtained are used for the investigation of the uniform Lipschitz stability of the zero solution of linear impulsive systems of differential equations.     

Adaptive chaos control and synchronization in only locally Lipschitz systems

In the existing results on chaos control and synchronization based on the adaptive controlling technique (ACT), a uniform Lipschitz condition on a given dynamical system is always assumed in advance. However, without this uniform Lipschitz condition, the ACT might be failed in both theoretical analysis and in numerical experiment. This Letter shows how to utilize the ACT to get a rigorous control for the system which is not uniformly Lipschitz but only locally Lipschitz, and even for the system which has unbounded trajectories. In fact, the ACT is proved to possess some limitation, which is actually induced by the nonlinear degree of the original system. Consequently, a piecewise ACT is proposed so as to improve the performance of the existing techniques.     

Kinetic characterization of strongly coupled systems

We propose a simple method to determine the local coupling strength Gamma experimentally, by linking the individual particle dynamics with the local density and crystal structure of a 2D plasma crystal. By measuring particle trajectories with high spatial and temporal resolution we obtain the first maps of Gamma and temperature at individual particle resolution. We employ numerical simulations to test this new method, and discuss the implications to characterize strongly coupled systems.     

Suppression of quantum scattering in strongly confined systems

We demonstrate that scattering of particles strongly interacting in three dimensions (3D) can be suppressed at low energies in a quasi-one-dimensional (1D) confinement. The underlying mechanism is the interference of the s- and p-wave scattering contributions with large s- and p-wave 3D scattering lengths being a necessary prerequisite. This low-dimensional quantum scattering effect might be useful in "interacting" quasi-1D ultracold atomic gases, guided atom interferometry, and impurity scattering in strongly confined quantum wire-based electronic devices.     

Chirped soliton interaction in strongly dispersion-managed wavelength-division-multiplexing systems

We theoretically analyze nonlinear interactions between chirped solitons in dispersion-managed wavelength-division-multiplexing (WDM) systems. We employ the perturbation method to evaluate frequency and chirp shifts caused by collisions among different WDM channels. It is shown that a chirped soliton suffers less frequency shift and time displacement than an ideal soliton, indicating its potential applicability for WDM systems.     

Noncrystallographic structural deformation levels in strongly excited systems

Conclusion Therefore, the analysis performed in the previous sections on the experimental data and results of modelling by the molecular dynamics method permits making a deduction on the possibility of the formation of strongly excited systems of noncrystallographic structural deformation levels during loading. As an experimental investigation showed, for all the kinds of static loading utilized their origination is associated with the pre-fracture stages. Crack propagation over the noncrystallographic interfacial boundaries of the fragments indicates this. Under shockwave loading the macroflux motion with the grains is also a new, larger-scale dynamic deformation level (compared with the dislocation level).Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 2, pp. 107–120, February, 1990.