Nonequilibrium Fock space for the electron transport problem

Based on the formalism of thermo field dynamics we propose a concept of nonequilibrium Fock space and nonequilibrium quasiparticles for quantum many-body system in nonequilibrium steady state. We develop a general theory as well as demonstrate the utility of the approach on the example of electron transport through the interacting region. The proposed approach is compatible with advanced methods of electronic structure calculations such as coupled cluster theory and configuration interaction

Thermal Bogoliubov transformation in nuclear structure theory

Thermal Bogoliubov transformation is an essential ingredient of the thermo field dynamics -- the real time formalism in quantum field and many-body theories at finite temperatures developed by H. Umezawa and coworkers. The approach to study properties of hot nuclei which is based on the extension of the well-known Quasiparticle-Phonon Model to finite temperatures employing the TFD formalism is presented. A distinctive feature of the QPM-TFD combination is a possibility to go beyond the standard approximations like the thermal Hartree-Fock or the thermal RPA ones.Comment: 8 pages, Proceedings of the International Bogolyubov Conference "Problems of Theoretical and Mathematical Physics", August 23 -- 27, 2009, Dubna, Russi

Velocity dependence of friction and Kramers relaxation rates

We study the influence of the velocity dependence of friction on the escape of a Brownian particle from the deep potential well ($E_{b} \gg k_{B}T$, $E_{b}$ is the barrier height, $k_{B}$ is the Boltzmann constant, $T$ is the bath temperature). The bath-induced relaxation is treated within the Rayleigh model (a heavy particle of mass $M$ in the bath of light particles of mass $m\ll M$) up to the terms of the order of $O(\lambda^{4})$, $\lambda^{2}=m/M\ll1$. The term $\sim 1$ is equivalent to the Fokker-Planck dissipative operator, and the term $\sim \lambda^{2}$ is responsible for the velocity dependence of friction. As expected, the correction to the Kramers escape rate in the overdamped limit is proportional to $\lambda^{2}$ and is small. The corresponding correction in the underdamped limit is proportional to $\lambda^{2}E_{b}/(k_{B}T)$ and is not necessarily small. We thus suggest that the effects due to the velocity-dependent friction may be of considerable importance in determining the rate of escape of an under- and moderately damped Brownian particle from a deep potential well, while they are of minor importance for an overdamped particle

Manifestation of nonequilibrium initial conditions in molecular rotation: the generalized J-diffusion model

In order to adequately describe molecular rotation far from equilibrium, we have generalized the J-diffusion model by allowing the rotational relaxation rate to be angular momentum dependent. The calculated nonequilibrium rotational correlation functions (CFs) are shown to decay much slower than their equilibrium counterparts, and orientational CFs of hot molecules exhibit coherent behavior, which persists for several rotational periods. As distinct from the results of standard theories, rotational and orientational CFs are found to dependent strongly on the nonequilibrium preparation of the molecular ensemble. We predict the Arrhenius energy dependence of rotational relaxation times and violation of the Hubbard relations for orientational relaxation times. The standard and generalized J-diffusion models are shown to be almost indistinguishable under equilibrium conditions. Far from equilibrium, their predictions may differ dramatically

Double difiusion in Ar-N2 Binary gas system at the constant value of temperature gradient

An experimental study of the diffusion-gravitational convection transition boundary in an Ar-N2 binary system at different pressures and a constant temperature gradient is performed. It is shown that the diflusion is replaced by the gravitational convection at a pressure p 0:5 MPa. In terms of the stability theory, a perturbation boundary line is determined, dividing the Rayleigh numbers plane into the regions of the diflusion and the convective mass transfer. The experimental data agree well with the theoretical values

Super-fermion representation of the Lindblad master equation for the electron transport problem

We discuss the use of super-fermion formalism to represent and solve quantum kinetic equations for the electron transport problem. Starting with the Lindblad master equation for the molecule connected to two metal electrodes, we convert the problem of finding the nonequilibrium steady state to the many-body problem with non-Hermitian Liouvillian in super-Fock space. We transform the Liouvillian to the normal ordered form, introduce nonequilibrium quasiparticles by a set of canonical nonunitary transformations and develop general many-body theory for the electron transport through the interacting region. The approach is applied to the electron transport through a single level. We consider a minimal basis hydrogen atom attached to two metal leads in Coulomb blockade regime (out of equilibrium Anderson model) within the nonequilibrium Hartree-Fock approximation as an example of the system with electron interaction. Our approach agrees with exact results given by the Landauer theory for the considered models.Comment: Accepted for publication in Journal of Chemical Physics (18 pages, 5 figures

Model for integrating monetary and fiscal policies to stimulate economic growth and sustainable debt dynamics

This article examines the main integration trends of the state's monetary and fiscal policy in influencing economic growth and maintaining the sustainability of public debt. It is argued that the relationship between these trends of macroeconomic regulation is predetermined, on the one hand, by the potentially negative impact of fiscal expansion from the point of view of inflation, and by the negative impact of a likely state default in failing to refinance the debt from the Ministry of Finance, on the other hand. The paper studies the selected array of statistical data using the fiscal policy multipliers concept, the relationship between the effect of increase/decrease in budget expenditures, the slowdown in economic activity and the efforts by the Central Bank to offset fiscal measures, on the one hand, and the ratio of an increase/decrease in budget revenues and debt expenditures used to finance the budget investments, on the other hand. It is revealed that the investments are effective if implementing budget expenditures in the presence of the GDP gap and unrealized expectations of economic agents, while reducing spending in such a situation will intensify the recession. The GDP growth determined by these investments should provide the tax effect sufficient to cover the expenses. Otherwise, there can be negative effects of debt that establishes the need for measures to refinance public debt by the Central Bank. The conclusions of the paper can be used to assess the possible integration of monetary and fiscal policy based on various states.peer-reviewe

Hadrons in Dense Resonance-Matter: A Chiral SU(3) Approach

A nonlinear chiral SU(3) approach including the spin 3/2 decuplet is developed to describe dense matter. The coupling constants of the baryon resonances to the scalar mesons are determined from the decuplet vacuum masses and SU(3) symmetry relations. Different methods of mass generation show significant differences in the properties of the spin-3/2 particles and in the nuclear equation of state.Comment: 28 pages, 9 figure