83 research outputs found
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 (,
is the barrier height, is the Boltzmann constant, is the
bath temperature). The bath-induced relaxation is treated within the Rayleigh
model (a heavy particle of mass in the bath of light particles of mass
) up to the terms of the order of ,
. The term is equivalent to the Fokker-Planck
dissipative operator, and the term is responsible for the
velocity dependence of friction. As expected, the correction to the Kramers
escape rate in the overdamped limit is proportional to and is
small. The corresponding correction in the underdamped limit is proportional to
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
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