arXiv subjects

Gustavo P. Saracco

Publications and source records attributed to Gustavo P. Saracco.

4 recordsLinked to original sources

arXiv2012

Damage Spreading in a Driven Lattice Gas Model

We studied damage spreading in a Driven Lattice Gas (DLG) model as a function of the temperature $T$, the magnitude of the external driving field $E$, and the lattice size. The DLG model undergoes an order-disorder second-order phase transition at the critical temperature $T_c(E)$, such that the ordered phase is characterized by high-density strips running along the direction of the applied field; while in the disordered phase one has a lattice-gas-like behaviour. It is found that the damage always spreads for all the investigated temperatures and reaches a saturation value $D_{sat}$ that depends only on $T$. $D_{sat}$ increases for $T T_c(E=\infty)$ and is free of finite-size effects. This behaviour can be explained as due to the existence of interfaces between the high-density strips and the lattice-gas-like phase whose roughness depends on $T$. Also, we investigated damage spreading for a range of finite fields as a function of $T$, finding a behaviour similar to that of the case with $E=\infty$.

cond-mat.stat-mech↗

arXiv2008

Dynamic behavior of the interface of strip-like structures in driven diffusive systems

The dynamic behavior of the interfaces in the standard and random driven lattice gas models (DLG and RDLG respectively) is investigated via numerical Monte Carlo simulations in two dimensions. For $T\lesssim T_c$, the average interface width of the strips ($W$) was measured as a function of the lattice size and the anisotropic shape factor. It was found that the saturation value $W^{2}_{sat}$ only depends on the lattice size parallel to the external field axis $L_y$ and exhibits two distinct regimes: $W^{2}_{sat}\propto \ln$ $L_y$ for low temperatures, that crosses over to $W^{2}_{sat}\propto L_y^{2α_I}$ near the critical zone, $α_I=1/2$ being the roughness exponent of the interface. By using the relationship $α_I=1/(1+Δ_I)$, the anisotropic exponent for the interface of the DLG model was estimated, giving $Δ_I\simeq 1$, in agreement with the computed value for anisotropic bulk exponent $Δ_B$ with a recently proposed theoretical approach. At the crossover region between both regimes, we observed indications of bulk criticality. The time evolution of $W$ at $T_c$ was also monitored and shows two growing stages: first one observes that $W \propto \ln$ $t$ for several decades, and in the following times one has $W\propto t^{β_I}$, where $β_{I}$ is the dynamic exponent of the interface width. By using this value we estimated the dynamic critical exponent of the correlation length in the perpendicular direction to the external field, giving $z_{\perp}^I\approx 4$, which is consistent with the dynamic exponent of the bulk critical transition $z_{\perp}^B$ in both theoretical approaches developed for the standard model. A similar scenario was also observed in the RDLG model, suggesting that both models may belong to the same universality class.

cond-mat.stat-mech↗

arXiv2007

Kinetics of self-induced aggregation in Brownian particles

We study a model of interacting random walkers that proposes a simple mechanism for the emergence of cooperation in group of individuals. Each individual, represented by a Brownian particle, experiences an interaction produced by the local unbalance in the spatial distribution of the other individuals. This interaction results in a nonlinear velocity driving the particle trajectories in the direction of the nearest more crowded regions; the competition among different aggregating centers generates nontrivial dynamical regimes. Our simulations show that for sufficiently low randomness, the system evolves through a coalescence behavior characterized by clusters of particles growing with a power law in time. In addition, the typical scaling properties of the general theory of stochastic aggregation processes are verified.

cond-mat.stat-mech↗

arXiv1999

Irreversible phase transitions induced by an oscillatory input

A novel kind of irreversible phase transitions (IPT's) driven by an oscillatory input parameter is studied by means of computer simulations. Second order IPT's showing scale invariance in relevant dynamic critical properties are found to belong to the universality class of directed percolation. In contrast, the absence of universality is observed for first order IPT's.

cond-mat.stat-mech↗