TEMPERATURE OF NONEQUILIBRIUM LATTICE SYSTEMS

2006 ◽  
Vol 17 (12) ◽  
pp. 1703-1715 ◽  
Author(s):  
ALBERTO PETRI ◽  
M. J. DE OLIVEIRA

We investigate the thermal quench of Ising and Potts models via Monte Carlo dynamics. We find that the local distribution of the site-site interaction energy has the same form as in the equilibrium case, a result that allows us to define an instantaneous temperature θ during the systems relaxation. We also find that, after an undercritical quench, θ equals the heat bath temperature in a finite time, while the total system energy is still decreasing due to the coarsening process.

2016 ◽  
Author(s):  
Ikuo Fukuda ◽  
Kei Moritsugu

AbstractThe Nosé-Hoover (NH) equation of motion is widely used in molecular dynamics simulations. It enables us to set a constant temperature and produce the canonical distribution for a target physical system. For the purpose of investigating the physical system under fluctuating temperature, we have introduced a coupled Nosé-Hoover equation in our previous work [J. Phys. A 48 455001 (2015)]. The coupled NH equation implements a fluctuating heat-bath temperature in the NH equation of the physical system, and also keeps a statistically complete description via an invariant measure of the total system composed of the physical system and a “temperature system”. However, a difficulty lies in that the time development of the physical system may not correspond to the realistic physical process, because of the need of a scaled time average to compute thermodynamical quantities. The current work gives a solution by presenting a new scheme, which is free from the scaled time but retains the statistical description. By use of simple model systems, we validate the current scheme and compare with the original scheme. The sampling property of the current scheme is also clarified to investigate the effect of function setting used for the distribution of the total system.


2003 ◽  
Vol 85 (5) ◽  
pp. 3271-3278 ◽  
Author(s):  
Andrzej Kolinski ◽  
Piotr Klein ◽  
Piotr Romiszowski ◽  
Jeffrey Skolnick

2014 ◽  
Author(s):  
Andreas Ammon ◽  
Tobias Hartung ◽  
Karl Jansen ◽  
Hernan Leövey ◽  
Andreas Griewank ◽  
...  

2004 ◽  
Vol 15 (09) ◽  
pp. 1249-1268 ◽  
Author(s):  
DENIS HORVÁTH ◽  
MARTIN GMITRA

Self-organized Monte Carlo simulations of 2D Ising ferromagnet on the square lattice are performed. The essence of the suggested simulation method is an artificial dynamics consisting of the well-known single-spin-flip Metropolis algorithm supplemented by a random walk on the temperature axis. The walk is biased towards the critical region through a feedback based on instantaneous energy and magnetization cumulants, which are updated at every Monte Carlo step and filtered through a special recursion algorithm. The simulations revealed the invariance of the temperature probability distribution function, once some self-organized critical steady regime is reached, which is called here noncanonical equilibrium. The mean value of this distribution approximates the pseudocritical temperature of canonical equilibrium. In order to suppress finite-size effects, the self-organized approach is extended to multi-lattice systems, where the feedback basis on pairs of instantaneous estimates of the fourth-order magnetization cumulant on two systems of different size. These replica-based simulations resemble, in Monte Carlo lattice systems, some of the invariant statistical distributions of standard self-organized critical systems.


1990 ◽  
Vol 60 (5-6) ◽  
pp. 889-889 ◽  
Author(s):  
P. Tamayo ◽  
R. C. Brower ◽  
W. Klein

1998 ◽  
Vol 538 ◽  
Author(s):  
C.C. Battaile ◽  
T.E. Buchheit ◽  
E.A. Holm ◽  
G.W. Wellman ◽  
M.K. Neilsen

AbstractThe microstructural evolution of heavily deformed polycrystalline Cu is simulated by coupling a constitutive model for polycrystal plasticity with the Monte Carlo Potts model for grain growth. The effects of deformation on boundary topology and grain growth kinetics are presented. Heavy deformation leads to dramatic strain-induced boundary migration and subsequent grain fragmentation. Grain growth is accelerated in heavily deformed microstructures. The implications of these results for the thermomechanical fatigue failure of eutectic solder joints are discussed.


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