arXiv subjects

Jian-Sheng Wang

Publications and source records attributed to Jian-Sheng Wang.

175 records · Page 10Linked to original sources

arXiv1998

Is the broad histogram random walk dynamics correct?

We show explicitly that the broad histogram single-spin-flip random walk dynamics does not give correct microcanonical average even in one dimension. The dynamics violates detailed balance condition by an amount which decreases with system size. As a result, in distribution different configurations with the same energy can have different probabilities. We propose a modified dynamics which ensures detailed balance and the histogram obtained from this dynamics is exactly flat.

cond-mat.stat-mech↗

arXiv1998

Transition Matrix Monte Carlo Reweighting and Dynamics

We study an induced dynamics in the space of energy of single-spin-flip Monte Carlo algorithm. The method gives an efficient reweighting technique. This dynamics is shown to have relaxation times proportional to the specific heat. Thus, it is plausible for a logarithmic factor in the correlation time of the standard 2D Ising local dynamics.

cond-mat.stat-mech↗

arXiv1998

Local, Cluster, and Transitional Monte Carlo Dynamics

We review the local Monte Carlo dynamics and Swendsen-Wang cluster algorithm. We introduce and analyze a new Monte Carlo dynamics known as transitional Monte Carlo. The transitional Monte Carlo algorithm samples energy probability distribution P(E) with a transition matrix obtained from single-spin-flip dynamics. We analyze the relaxation dynamics master equation, d P(E, t)/ dt = sum{E'} T(E,E') P(E',t), associated with Ising model in d dimensions. In one dimension, we obtain an exact solution. We show in all dimensions in the continuum limit the dynamics is governed by the partial differential equation d P/dt' = d^2 P / d x^2 + x dP/dx + P. where x and t' are rescaled energy deviation from the equilibrium value and rescaled time, respectively. This equation is readily solved. Thus, we have a complete understanding of the dynamics.

cond-mat.stat-mech↗

arXiv1997

Nonequilibrium relaxation of the two-dimensional Ising model: Series-expansion and Monte Carlo studies

We study the critical relaxation of the two-dimensional Ising model from a fully ordered configuration by series expansion in time t and by Monte Carlo simulation. Both the magnetization (m) and energy series are obtained up to 12-th order. An accurate estimate from series analysis for the dynamical critical exponent z is difficult but compatible with 2.2. We also use Monte Carlo simulation to determine an effective exponent, z_eff(t) = - {1/8} d ln t /d ln m, directly from a ratio of three-spin correlation to m. Extrapolation to t = infinity leads to an estimate z = 2.169 +/- 0.003.

cond-mat.stat-mech↗

arXiv1997

Extended series expansions for random sequential adsorption

We express the coverage (occupation fraction) $θ$, in powers of time $t$ for four models of two-dimensional lattice random sequential adsorption (RSA) to very high orders by improving an algorithm developed by the present authors [J. Phys. A 29, L177 (1996)]. Each of these series is, to the best of our knowledge, the longest at the present. We analyze the series and deduce accurate estimates for the jamming coverage of the models.

cond-mat↗

arXiv1997

Random Sequential Adsorption, Series Expansion and Monte Carlo Simulation

Random sequential adsorption is an irreversible surface deposition of extended objects. In systems with continuous degrees of freedom coverage follows a power law, theta(t) = theta_J - c t^{-alpha}, where the exponent alpha depends on the geometric shape (symmetry) of the objects. Lattice models give typically exponential saturation to jamming coverage. We discuss how such function theta(t) can be computed by series expansions and analyzed with Pade approximations. We consider the applications of efficient Monte Carlo computer simulation method (event-driven method) to random sequential adsorptions with high precision and at very long-time scale.

cond-mat.stat-mech↗

arXiv1996

Series expansion studies of random sequential adsorption with diffusional relaxation

We obtain long series (28 terms or more) for the coverage (occupation fraction) $θ$, in powers of time $t$ for two models of random sequential adsorption with diffusional relaxation using an efficient algorithm developed by the authors. Three different kinds of analyses of the series are performed for a wide range of $γ$, the rate of diffusion of the adsorbed particles, to investigate the power law approach of $θ$ at large times. We find that the primitive series expansions in time $t$ for $θ$ capture rich short and intermediate time kinetics of the systems very well. However, we see that the series are still not long enough to extract the kinetics at large times for general $γ$. We have performed extensive computer simulations employing an efficient event-driven algorithm to confirm the $t^{-1/2}$ saturation approach of $θ$ at large times for both models, as well as to investigate the short and intermediate time behaviors of the systems.

cond-mat↗

arXiv1996

Kinetics and Jamming Coverage in a Random Sequential Adsorption of Polymer Chains

Using a highly efficient Monte Carlo algorithm, we are able to study the growth of coverage in a random sequential adsorption (RSA) of self-avoiding walk (SAW) chains for up to 10^{12} time steps on a square lattice. For the first time, the true jamming coverage (theta_J) is found to decay with the chain length (N) with a power-law theta_J propto N^{-0.1}. The growth of the coverage to its jamming limit can be described by a power-law, theta(t) approx theta_J -c/t^y with an effective exponent y which depends on the chain length, i.e., y = 0.50 for N=4 to y = 0.07 for N=30 with y -> 0 in the asymptotic limit N -> infinity.

cond-mat↗

arXiv1995

An algorithm for series expansions based on hierarchical rate equations

We propose a computational method to obtain series expansions in powers of time for general dynamical systems described by a set of hierarchical rate equations. The method is generally applicable to problems in both equilibrium and nonequilibrium statistical mechanics such as random sequential adsorption, diffusion-reaction dynamics, and Ising dynamics. New result of random sequential adsorption of dimers on a square lattice is presented.

cond-mat↗

arXiv1995

Cluster Monte Carlo algorithms and their applications

We review the background of the cluster algorithms in Monte Carlo simulation of statistical physics problems. One of the first such successful algorithm was developed by Swendsen and Wang eight years ago. In contrast to the local algorithms, cluster algorithms update dynamical variables in a global fashion. Therefore, large changes are made in a single step. The method is very efficient, especially near the critical point of a second-order phase transition. Studies of various statistical mechanics models and some generalizations of the algorithm will be briefly reviewed. We mention applications in other fields, especially in imaging processing.

cond-mat↗

arXiv1995

Rotationally symmetric ordered phase in the three-state antiferromagnetic Potts model

We investigate the three-state antiferromagnetic Potts model on a simple cubic lattice with a cluster flipping Monte Carlo simulation algorithm in the temperature region below the transition into disorder at T_{c1}. We find both the well established broken-sublattice-symmetry (BSS) phase at low temperature and a new, rotationally symmetric phase at higher temperature, but below T_{c1}. The properties of the second phase and the transition temperature to the BSS phase are in disagreement with recent cluster-variation and Monte Carlo simulation results, but in agreement with simulations by Kolesik and Suzuki.

cond-mat↗

arXiv1994

Anisotropic Finite-Size Scaling Analysis of a Two-Dimensional Driven Diffusive System

Extensive Monte Carlo simulation results of the standard two-dimensional driven diffusive systems are obtained using a multispin coding technique. The nonequilibrium phase transition is analyzed with anisotropic finite-size scaling, both at the critical point and off the critical point. The field-theoretical values of critical exponents fit the data well. (TeX file size 22kBytes, figures 24kBytes)

cond-mat↗

arXiv1993

Locally Frozen Defects in Random Sequential Adsorption with Diffusional Relaxation

Random sequential adsorption with diffusional relaxation, of two by two square objects on the two-dimensional square lattice is studied by Monte Carlo computer simulation. Asymptotically for large lattice sizes, diffusional relaxation allows the deposition process to reach full coverage. The coverage approaches the full occupation value, 1, as a power-law with convergence exponent near 1/2. For a periodic lattice of finite (even) size $L$, the final state is a frozen random rectangular grid of domain walls connecting single-site defects. The domain sizes saturate at L**0.8. Prior to saturation, i.e., asymptotically for infinite lattice, the domain growth is power-law with growth exponent near, or possibly somewhat smaller than, 1/2.

cond-mat↗