Search results for "Equilibrium thermodynamics"
showing 10 items of 132 documents
Thermodynamic formalism and linear response theory for non-equilibrium steady states
2016
We study the linear response in systems driven away from thermal equilibrium into a nonequilibrium steady state with nonvanishing entropy production rate. A simple derivation of a general response formula is presented under the condition that the generating function describes a transformation that (to lowest order) preserves normalization and thus describes a physical stochastic process. For Markov processes we explicitly construct the conjugate quantities and discuss their relation with known response formulas. Emphasis is put on the formal analogy with thermodynamic potentials and some consequences are discussed.
Atomistic Simulation of Transport Phenomena in Simple and Complex Fluids and Fluid Mixtures
2003
Computer simulations of fluids in thermal equilibrium can yield information on transport coefficients such as self—diffusion and interdiffusion coefficients, viscosity, and thermal conductivity. While the estimation of self—diffusion coefficients from the mean square displacements of the respective particles is rather straightforward, the estimation of other transport coefficients is less straightforward, and can be based on either an analysis of time correlation functions of the appropriate collective variables, or on nonequilibrium techniques where the linear response to appropriate perturbations is measured.
Gibbs equation in the nonlinear nonequilibrium thermodynamics of dilute nonviscous gases
2003
AbstractThis paper deals with the derivation of the Gibbs equation for a nonviscous gas in the presence of heat flux. The analysis aims to shed some light on the physical interpretation of thermodynamic potentials far from equilibrium. Two different definitions for the chemical potential and thermodynamic pressure far from equilibrium are introduced: nonequilibrium chemical potential and nonequilibrium thermodynamic pressure at constant heat flux q and nonequilibrium chemical potential and nonequilibrium thermodynamic pressure at constant J = Vq, where V is the specific volume.
Fast relaxation phenomena and slow mode in extended thermodynamics of superfluids
2003
A macroscopic monofluid model of liquid helium II which is based on extended thermodynamics was formulated in previous works, both in the presence and in the absence of dissipative phenomena. In all these studies, the time evolution of the nonequilibrium stress tensor was neglected, putting the relaxation times @t"0 and @t"2 of the nonequilibrium pressure and of the stress deviator equal to zero. In this work, the time evolution of these fields is not neglected and the complete model with 14 fields is studied, in the linear approximation. The propagation of waves is studied and a dispersion relation of degree 14 is obtained. The solutions of this equation are carried out, perturbing the sol…
Electronic transport in molecular junctions : The generalized Kadanoff–Baym ansatz with initial contact and correlations
2021
The generalized Kadanoff-Baym ansatz (GKBA) offers a computationally inexpensive approach to simulate out-of-equilibrium quantum systems within the framework of nonequilibrium Green's functions. For finite systems the limitation of neglecting initial correlations in the conventional GKBA approach has recently been overcome [Phys. Rev. B 98, 115148 (2018)]. However, in the context of quantum transport the contacted nature of the initial state, i.e., a junction connected to bulk leads, requires a further extension of the GKBA approach. In this work, we lay down a GKBA scheme which includes initial correlations in a partition-free setting. In practice, this means that the equilibration of the …
Transport coefficients in desalting processes by electrodialysis
2011
Abstract In this work a thermodynamic analysis on the transport equations in the processes of electrodiffusion (EF) and electrodialysis (ED) has been developed. The transport equations are classified in two sets according to the information they contain: i ) fundamental and ii ) complementary. We determine that there are four fundamental transport coefficients needed to characterize these membrane systems. We also conclude that this number is not reduced to three when the Onsager reciprocal relation (ORR) is assumed. I have also obtained a new expression for the concentration rate in EF and ED processes from the mass and volume balance. This relation provides a new way for evaluating the ap…
An Interfacial Thermodynamic Model for the Oxidation Kinetics of a Metal: Epitaxial Stress Effects
2004
Coupled Modelling of ZrO 2 /α-Zr(O) Layers Growth under Thermal and Mechanical Gradients
2019
The oxidation process of a nuclear reactor fuel rod clad made of zirconium is simulated. It is assumed that the oxygen is transported by anionic diffusion in the zirconia layer (ZrO2). Part of this oxygen reacts at the interface between the zirconia layer and the metal, while the rest diffuses in the oxygen-enriched metal volume (α-Zr(O)) to the core of the metal by an interstitial mechanism. The model is based on the thermodynamics of irreversible processes and takes into account the influence of driving forces on the oxygen migration in the metal such as the oxygen concentration gradient, the temperature gradient [1] and the mechanical stress gradient [2]. The growth of both ZrO2 and α-Zr…
Equilibrium fluid-crystal interfacial free energy of bcc-crystallizing aqueous suspensions of polydisperse charged spheres
2015
The interfacial free energy is a central quantity in crystallization from the meta-stable melt. In suspensions of charged colloidal spheres, nucleation and growth kinetics can be accurately measured from optical experiments. In previous work, from this data effective non-equilibrium values for the interfacial free energy between the emerging bcc-nuclei and the adjacent melt in dependence on the chemical potential difference between melt phase and crystal phase were derived using classical nucleation theory. A strictly linear increase of the interfacial free energy was observed as a function of increased meta-stability. Here, we further analyze this data for five aqueous suspensions of charg…
Merging Features from Green's Functions and Time Dependent Density Functional Theory: A Route to the Description of Correlated Materials out of Equil…
2016
We propose a description of nonequilibrium systems via a simple protocol that combines exchange-correlation potentials from density functional theory with self-energies of many-body perturbation theory. The approach, aimed to avoid double counting of interactions, is tested against exact results in Hubbard-type systems, with respect to interaction strength, perturbation speed and inhomogeneity, and system dimensionality and size. In many regimes, we find significant improvement over adiabatic time dependent density functional theory or second Born nonequilibrium Green's function approximations. We briefly discuss the reasons for the residual discrepancies, and directions for future work.