AN INVESTIGATION OF THE PHASE TRANSITIONS OF A FAMILY OF PROBABILISTIC AUTOMATA

2004 ◽  
Vol 07 (01) ◽  
pp. 93-123
Author(s):  
HEINZ MÜHLENBEIN ◽  
THOMAS AUS DER FÜNTEN
Keyword(s):  
Phase Transitions ◽  
Stationary Distribution ◽  
Classification Scheme ◽  
Mean Field ◽  
Finite Size ◽  
Order Parameters ◽  
Finite Size Scaling ◽  
Probabilistic Cellular Automata ◽  
Probabilistic Automata ◽  
Major Transitions

We investigate a family of totalistic probabilistic cellular automata (PCA) which depend on three parameters. For the uniform random neighborhood and for the symmetric 1D PCA the exact stationary distribution is computed for all finite n. This result is used to evaluate approximations (uni-variate and bi-variate marginals). It is proven that the uni-variate approximation (also called mean-field) is exact for the uniform random neighborhood PCA. The exact results and the approximations are used to investigate phase transitions. We compare the results of two order parameters, the uni-variate marginal and the normalized entropy. Sometimes different transitions are indicated by the Ehrenfest classification scheme. This result shows the limitations of using just one or two order parameters for detecting and classifying major transitions of the stationary distribution. Furthermore, finite size scaling is investigated. We show that extrapolations to n=∞ from numerical calculations of finite n can be misleading in difficult parameter regions. Here, exact analytical estimates are necessary.

CLASSIFICATION THEORY FOR PHASE TRANSITIONS

1993 ◽  
Vol 07 (26) ◽  
pp. 4371-4387 ◽  
Author(s):  
R. HILFER
Keyword(s):  
Phase Transitions ◽  
Classification Scheme ◽  
Equilibrium Phase ◽  
Finite Size ◽  
Second Order ◽  
Classification Theory ◽  
Special Role ◽  
Finite Size Scaling ◽  
First Order ◽  
Size Scaling

A refined classification theory for phase transitions in thermodynamics and statistical mechanics in terms of their orders is introduced and analyzed. The refined thermodynamic classification is based on two independent generalizations of Ehrenfests traditional classification scheme. The statistical mechanical classification theory is based on generalized limit theorems for sums of random variables from probability theory and the newly defined block ensemble limit. The block ensemble limit combines thermodynamic and scaling limits and is similar to the finite size scaling limit. The statistical classification scheme allows for the first time a derivation of finite size scaling without renormalization group methods. The classification distinguishes two fundamentally different types of phase transitions. Phase transitions of order λ>1 correspond to well known equilibrium phase transitions, while phase transitions with order λ<1 represent a new class of transitions termed anequilibrium transitions. The generalized order λ varies inversely with the strength of fluctuations. First order and second order transitions play a special role in both classification schemes. First order transitions represent a limiting case separating equilibrium and anequilibrium transitions. The special role or second order transitions is shown to be related to the breakdown of hyperscaling. For anequilibrium transitions the nature of the heat bath in the canonical ensemble becomes important.

FLUCTUATION EFFECTS IN A CLASS OF SYSTEMS WITH TWO ORDER PARAMETERS

1993 ◽  
Vol 07 (27) ◽  
pp. 1725-1731 ◽  
Author(s):  
L. DE CESARE ◽  
I. RABUFFO ◽  
D.I. UZUNOV
Keyword(s):  
Phase Transition ◽  
Renormalization Group ◽  
Phase Transitions ◽  
Order Phase Transition ◽  
Mean Field ◽  
Ising Models ◽  
Order Parameters ◽  
The Mean ◽  
Fluctuation Effects ◽  
Second Order Phase Transition

The phase transitions described by coupled spin -1/2 Ising models are investigated with the help of the mean field and the renormalization group theories. Results for the type of possible phase transitions and their fluctuation properties are presented. A fluctuation-induced second-order phase transition is predicted.

scholarly journals Transmuted Finite-size Scaling at First-order Phase Transitions

2014 ◽  
Vol 57 ◽  
pp. 68-72 ◽  
Author(s):  
Marco Mueller ◽  
Wolfhard Janke ◽  
Desmond A. Johnston
Keyword(s):  
Phase Transitions ◽  
Finite Size ◽  
Finite Size Scaling ◽  
First Order ◽  
Size Scaling ◽  
First Order Phase

scholarly journals PERCOLATION AND FINITE SIZE SCALING IN SEVEN DIMENSIONS

2004 ◽  
Vol 15 (09) ◽  
pp. 1321-1325
Author(s):  
LOTFI ZEKRI
Keyword(s):  
Phase Transitions ◽  
Ising Model ◽  
Numerical Investigation ◽  
Critical Exponents ◽  
Finite Size ◽  
Critical Dimension ◽  
Finite Size Scaling ◽  
Size Scaling ◽  
Hypercubic Lattice

Numerical investigation of critical exponents on a hypercubic lattice with Ld random sites with L up to 33 and d up to 7 showed that above the critical dimension the phase transitions in Ising model and percolation are not alike.

DYNAMIC SCALING FOR FIRST-ORDER PHASE TRANSITIONS

2000 ◽  
Vol 11 (03) ◽  
pp. 553-559
Author(s):  
BANU EBRU ÖZOĞUZ ◽  
YIĞIT GÜNDÜÇ ◽  
MERAL AYDIN
Keyword(s):  
Phase Transitions ◽  
Finite Size ◽  
Two Dimensions ◽  
Dynamic Scaling ◽  
Finite Size Scaling ◽  
Potts Models ◽  
Time Dynamics ◽  
First Order ◽  
Short Time ◽  
First Order Phase

The critical behavior in short time dynamics for the q = 6 and 7 state Potts models in two-dimensions is investigated. It is shown that dynamic finite-size scaling exists for first-order phase transitions.

Phase Transitions, Critical Phenomena, and Finite-Size Scaling

2019 ◽  
pp. 111-176
Author(s):  
Hans-Peter Eckle
Keyword(s):  
Phase Transition ◽  
Phase Transitions ◽  
Critical Phenomena ◽  
Quantum Phase Transitions ◽  
Finite Size ◽  
System Size ◽  
Thermal Fluctuations ◽  
Finite Size Scaling ◽  
Size Scaling

Interacting many-particle systems may undergo phase transitions and exhibit critical phenomena in the limit of infinite system size, while the precursors of these phenomena are studied in the theory of finite-size scaling. After surveying the basic notions of phases, phase diagrams, and phase transitions, this chapter focuses on critical behaviour at a second-order phase transition. The Landau-Ginzburg theory and the concept of scaling prepare readers for an elementary introduction to the concepts of the renormalization group, followed by an introduction into the field of quantum phase transitions where quantum fluctuations take over the role of thermal fluctuations.

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