6 research outputs found
Coarse-graining schemes for stochastic lattice systems with short and long-range interactions
We develop coarse-graining schemes for stochastic many-particle microscopic
models with competing short- and long-range interactions on a d-dimensional
lattice. We focus on the coarse-graining of equilibrium Gibbs states and using
cluster expansions we analyze the corresponding renormalization group map. We
quantify the approximation properties of the coarse-grained terms arising from
different types of interactions and present a hierarchy of correction terms. We
derive semi-analytical numerical schemes that are accompanied with a posteriori
error estimates for coarse-grained lattice systems with short and long-range
interactions.Comment: 31 pages, 2 figure
Current reservoirs in the simple exclusion process
We consider the symmetric simple exclusion process in the interval
with additional birth and death processes respectively on , , and
. The exclusion is speeded up by a factor , births and deaths
by a factor . Assuming propagation of chaos (a property proved in a
companion paper "Truncated correlations in the stirring process with births and
deaths") we prove convergence in the limit to the linear heat
equation with Dirichlet condition on the boundaries; the boundary conditions
however are not known a priori, they are obtained by solving a non linear
equation. The model simulates mass transport with current reservoirs at the
boundaries and the Fourier law is proved to hold
Multispecies virial expansions
We study the virial expansion of mixtures of countably many different types of particles. The main tool is the LagrangeâGood inversion formula, which has other applications such as counting coloured trees or studying probability generating functions in multi-type branching processes. We prove that the virial expansion converges absolutely in a domain of small densities. In addition, we establish that the virial coefficients can be expressed in terms of two-connected graphs
Large deviations for the macroscopic motion of an interface
We study the most probable way an interface moves on a macroscopic scale from an initial to a final position within a fixed time in the context of large deviations for a stochastic microscopic lattice system of Ising spins with Kac interaction evolving in time according to Glauber (non-conservative) dynamics. Such interfaces separate two stable phases of a ferromagnetic system and in the macroscopic scale are represented by sharp transitions. We derive quantitative estimates for the upper and the lower bound of the cost functional that penalizes all possible deviations and obtain explicit error terms which are valid also in the macroscopic scale. Furthermore, using the result of a companion paper about the minimizers of this cost functional for the macroscopic motion of the interface in a fixed time, we prove that the probability of such events can concentrate on nucleations should the transition happen fast enough
Convergence of density expansions of correlation functions and the Ornstein-Zernike equation
We prove absolute convergence of the multi-body correlation functions as a power series in the density uniformly in their arguments. This is done by working in the context of the cluster expansion in the canonical ensemble and by expressing the correlation functions as the derivative of the logarithm of an appropriately extended partition function. In the thermodynamic limit, due to combinatorial cancellations, we show that the coeffi- cients of the above series are expressed by sums over some class of two-connected graphs. Furthermore, we prove the convergence of the density expansion of the âdirect correlation functionâ which is based on a completely different approach and it is valid only for some inte- gral norm. Precisely, this integral norm is suitable to derive the Ornstein-Zernike equation. As a further outcome, we obtain a rigorous quantification of the error in the Percus-Yevick approximation
Finite volume corrections and decay of correlations in the canonical ensemble
We consider a classical system of N particles confined in a box Îââd interacting via a finite range pair potential. Given the validity of the cluster expansion in the canonical ensemble we compute the error between the finite and the infinite volume free energy and estimate it to be bounded by the area of the surface of the boxâs boundary over its volume. We also compute the truncated two-point correlation function and find that the contribution from the ideal gas case is of the order 1/|Î| plus an exponentially small error with the distance