Dependence of equilibrium properties of channeled particles on the transverse quasitemperature

We use methods of nonequilibrium thermodynamics to investigate the quasiequilibrium and kinetic characteristics of channeled particles regarded as a separate thermodynamic subsystem. For the channeled particles, we derive the energy—momentum balance equation in the moving coordinate system and show that the solution of the balance equation provides an expression for the main thermodynamic parameter, the transverse quasitemperature of the channeled-particle subsystem. We study the quasiequilibrium angular distribution of particles after their passage through a thin single crystal, the quasiequilibrium distribution over the particle exit angles under backscattering conditions, and also the rate constant for the nonequilibrium (dechanneling) process at large deviations of the system as a whole from the thermodynamic equilibrium. We discuss a measurement method for the particle beam transverse temperature over the peak height of the angular particle distribution found in the framework of a “shoot-through” experiment. __________ Translated from Teoreticheskaya i Matematicheskaya Fizika, Vol. 146, No. 3, pp. 509–524, March, 2006.     

Thermodynamical Averages For The Ising Model And Spectral Invariants Of Toeplitz Matrices

We derive a general formula giving a representation of the partition function of the one-dimensional Ising model of a system of N particles in the form of an explicitly defined functional of the spectral invariants of finite submatrices of a certain infinite Toeplitz matrix. We obtain an asymptotic representation of the partition function for large N, which can be a base for explicitly calculating some thermodynamic averages, for example, the specific free energy, in the case of a general translation-invariant spin interaction (not necessarily only between nearest neighbors). We estimate the partition function from above and below in the plane of the complex variable β (β is the inverse temperature) and consider the conditions under which these estimates are asymptotically equivalent as N → ∞

     

Thermalization of Displacement Cascades in Solids and the Thermal Spike Model

We investigate the thermalization of low-energy cascades of displacements in solids using methods of nonequilibrium statistical thermodynamics. We investigate the time evolution of the quasi temperature of cascade particles taking the phonon scattering on dislodged atoms and the thermal recombination of defects into account. We use the obtained quasi-temperature time dependence to study the activated process—sputtering in the thermal spike region.     

Permittivity and one-particle distribution functions in the thermodynamics of a coulomb system

Using the grand canonical distribution and the virial theorem, we show that the Gibbs thermodynamic potential of a nonrelativistic system of charged particles is uniquely determined by its permittivity and the distribution functions of electrons and nuclei without using perturbation theory. This means that consistent approximations for the permittivity and one-particle distribution functions of electrons and nuclei must be used to calculate thermodynamic functions of the Coulomb system. To construct such selfconsistent approximations, we propose using a decoupling procedure based on separating the “connected” and “regular” parts of the temperature Green’s functions in the equations of motion. We consider the self-consistent Hartree-Fock approximation corresponding to this procedure.     

Emergent behaviors of a thermodynamic Cucker-Smale flock with a time-delay on a general digraph

We present emergent flocking dynamics of a thermodynamic Cucker-Smale (TCS) flock on a general digraph with spanning trees under the effect of communication time-delays. The TCS model describes a temporal evolution of mechanical and thermodynamic observables such as position, velocity and temperature of CS particles. In this paper, we study how variations in mechanical and thermodynamic variables can decay to zero along a time-independent network with position dependent weights from initial state configuration. For this, we provide a sufficient framework for a mechanical and thermodynamical flocking in terms of initial configuration, network topology, and system parameters. We also present several numerical examples and compare them with analytical results.     

Nonequilibrium statistical thermodynamics of cascade processes in solids: the quasi temperature of cascade particles

Displacement cascades in solids are investigated in the framework of nonequilibrium statistical thermodynamics. The quasi temperature of a subsystem of cascade particles in metals and semiconductors is derived using the energy balance equation for a cascade process.     

Thermodynamics of the model of equal spin-spin interactions

We consider the thermodynamics of the model of equal spin-spin interactions. We obtain exact expressions for the correlation functions and heat capacity of finite clusters applicable in the entire range of temperature and external fields. We analyze the obtained thermodynamic characteristics depending on the interaction parameters, the external magnetic field, and the number of particles in the cluster. We find an anomalous behavior of the heat capacity and other thermodynamic quantities due to elementary spin gap excitations occurring in the spectrum. The absence of a long-range order in the system is ensured by the presence of topological excitations (solitons). We study the effect of an anisotropic interaction parameter on the soliton structure.     

Nonequilibrium statistical thermodynamics of channeled particles. The transverse quasitemperature

Fast charged particles moving in a crystal in the channeling regime are treated as an independent thermodynamic subsystem for which energy acnd momentum balance equations are derived in the comoving coordinate system. It is shown that the solution of these equations gives an expression for the transverse quasitemperature of the channeled particles in terms of the fundamental parameters of the nicroscopic theory. If the electron scattering is quasielastic, then at a penetration depth of the order of the coherence length the system as a whole remains in strong disequilibrium despite the attainment of internal equilibrium in the subsystem of the particles. There is a large difference between the thermodynamic parameters of the channeled particles and of the thermal reservoir.A. A. Baikov Institute of Metallurgy, Russian Academy of Sciences. Translated from Teoreticheskaya i Matematicheskaya Fizika, Vol. 102, No. 1, pp. 106–118, January, 1995.     

Passage to diffusion chaos in a model of an ecological system

We carry out analytical and numerical analysis of a model of an ecological system described by a system of nonlinear partial differential equations of reaction-diffusion type. We find conditions for the bifurcation of periodic spatially homogeneous and inhomogeneous solutions from the thermodynamic branch of the system. We show that the passage to diffusion chaos in the model occurs, in complete agreement with the universal Feigenbaum-Sharkovskii-Magnitskii bifurcation theory, via a subharmonic cascade of bifurcations of stable limit cycles.     

The thermodynamic limit of quantum Coulomb systems Part II. Applications

In a previous paper [C. Hainzl, M. Lewin, J.P. Solovej, The thermodynamic limit of quantum Coulomb systems. Part I. General theory, Adv. Math. (2009), doi:10.1016/j.aim.2008.12.010 (this issue)], we have developed a general theory of thermodynamic limits. We apply it here to three different Coulomb quantum systems, for which we prove the convergence of the free energy per unit volume.The first system is the crystal for which the nuclei are classical particles arranged periodically in space and only the electrons are quantum particles. We recover and generalize a previous result of Fefferman. In the second example, both the nuclei and the electrons are quantum particles, submitted to a periodic magnetic field. We thereby extend a seminal result of Lieb and Lebowitz. Finally, in our last example we take again classical nuclei but optimize their position. To our knowledge such a system was never treated before.The verification of the assumptions introduced in [C. Hainzl, M. Lewin, J.P. Solovej, The thermodynamic limit of quantum Coulomb systems. Part I. General theory, Adv. Math. (2009), doi:10.1016/j.aim.2008.12.010 (this issue)] uses several tools which have been introduced before in the study of large quantum systems. In particular, an electrostatic inequality of Graf and Schenker is one main ingredient of our new approach.     

A new approach to the cascade theory

The cascade theory of cosmic rays is investigated from a new point of view; we deal with the number of particles produced in a certain thickness of matter, the energy of each particle being greater than E at the point of its production. This new approach leads to an elegant asymptotic theory for large thicknesses and it is better adapted to the interpretation of experiments in nuclear emulsions.     

Cascades of Hopf bifurcations from boundary delay

We consider a 1-dimensional reaction-diffusion equation with nonlinear boundary conditions of logistic type with delay. We deal with non-negative solutions and analyze the stability behavior of its unique positive equilibrium solution, which is given by the constant function u≡1. We show that if the delay is small, this equilibrium solution is asymptotically stable, similar as in the case without delay. We also show that, as the delay goes to infinity, this equilibrium becomes unstable and undergoes a cascade of Hopf bifurcations. The structure of this cascade will depend on the parameters appearing in the equation. This equation shows some dynamical behavior that differs from the case where the nonlinearity with delay is in the interior of the domain.     

Singularities of the thermodynamic potential under second-order phase transitions due to the interband electron-phonon interaction

We consider phase transitions in crystals with a strong interband electron-phonon interaction. We investigate the thermodynamic potential of the system using the method of temperature Green’s functions, which takes quantum and thermal fluctuations into account. We show that in the absence of striction, these phase transitions are realized as a sequence of second-order phase transitions in each of which the thermodynamic potential has a logarithmic singularity, as in the Onsager model. This suggests that this singularity is characteristic of all second-order phase transitions. We show that the energy preference of the transition to the ordered phase is ensured by the electron coupling to coherent displacements of ions along normal coordinates of the phonon modes. We calculate the limit value of the energy decrease in the ordered phase compared with the symmetric phase as T → 0 K. __________ Translated from Teoreticheskaya i Matematicheskaya Fizika, Vol. 157, No. 2, pp. 273–285, November, 2008.     

Quantization dimension and temperature function for recurrent self-similar measures

We determine the quantization dimension function for the image measure supported on a recurrent self-similar set of an ergodic Markov measure, and its relationship with the temperature function of the thermodynamic formalism arising in multifractal analysis is established.     

Statistical mechanics of classical particles with logarithmic interactions

The inhomogeneous mean-field thermodynamic limit is constructed and evaluated for both the canonical thermodynamic functions and the states of systems of classical point particles with logarithmic interactions in two space dimensions. The results apply to various physical models of translation invariant plasmas, gravitating systems, as well as to planar fluid vortex motion. For attractive interactions a critical behavior occurs which can be classified as an extreme case of a second-order phase transition. To include in particular attractive interactions a new inequality for configurational integrals is derived from the arithmetic-geometric mean inequality. The method developed in this paper is easily seen to apply as well to systems with fairly general interactions in all space dimensions. In addition, it also provides us with a new proof of the Trudinger-Moser inequality known from differential geometry – in its sharp form.     

Sulla regolarità dei processi termodinamici per alcuni materiali con memoria

Summary We study the thermodynamic restrictions for a class of materials which have memory and emphasize that the different regularity of the temperature gradient brings to a different definition of material state and to different properties for thermodynamic potentials.

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Lavoro eseguito nell'ambito del G.N.F.M. del C.N.R.     

Thermodynamic limit for the invariant measures in supercritical zero range processes

We prove a strong form of the equivalence of ensembles for the invariant measures of zero range processes conditioned to a supercritical density of particles. It is known that in this case there is a single site that accomodates a macroscopically large number of the particles in the system. We show that in the thermodynamic limit the rest of the sites have joint distribution equal to the grand canonical measure at the critical density. This improves the result of Großkinsky, Schütz and Spohn, where convergence is obtained for the finite dimensional marginals. We obtain as corollaries limit theorems for the order statistics of the components and for the fluctuations of the bulk.     

Monotonicity properties of the quantum mechanical particle density: an elementary proof

The negative quantum mechanical particle density in its dependence on the potential in the Hamiltonian is a nonlinear operator. We give an explicit proof of the monotonicity of this operator for a large class of admissible thermodynamic equilibrium distribution functions. In particular the zero temperature case is included.     

Integral equations for correlation functions of a quantum one-dimensional Bose gas

The large-time, long-distance behavior of the temperature correlation functions of a quantum one-dimensional Bose gas is considered. We obtain integral equations, which are closely related to the thermodynamic Bethe ansatz equations and whose solutions describe asymptotic expressions. In the low-temperature limit, the solutions of these equations are expressed through observables of the model. Translated from Teoreticheskaya i Matematicheskaya Fizika, Vol. 121, No. 1, pp. 117–138, October, 1999.