First-order phase transition of the exchange-interaction model studied by the Handscomb quantum Monte Carlo method

1998 ◽  
Vol 57 (9) ◽  
pp. 5009-5012 ◽  
Author(s):  
Y. C. Chen
Keyword(s):  
Phase Transition ◽  
Monte Carlo ◽  
Monte Carlo Method ◽  
Order Phase Transition ◽  
Quantum Monte Carlo ◽  
Interaction Model ◽  
First Order ◽  
First Order Phase Transition ◽  
Quantum Monte Carlo Method ◽  
First Order Phase

scholarly journals ISING MODEL SPIN S = 1 ON DIRECTED BARABÁSI–ALBERT NETWORKS

2006 ◽  
Vol 17 (09) ◽  
pp. 1267-1272 ◽  
Author(s):  
F. W. S. LIMA
Keyword(s):  
Phase Transition ◽  
Monte Carlo ◽  
Ising Model ◽  
Order Phase Transition ◽  
Decay Time ◽  
Arrhenius Law ◽  
Disorder Phase Transition ◽  
First Order ◽  
First Order Phase Transition ◽  
First Order Phase

On directed Barabási–Albert networks with two and seven neighbours selected by each added site, the Ising model with spin S = 1/2 was seen not to show a spontaneous magnetisation. Instead, the decay time for flipping of the magnetisation followed an Arrhenius law for Metropolis and Glauber algorithms, but for Wolff cluster flipping the magnetisation decayed exponentially with time. On these networks the Ising model spin S = 1 is now studied through Monte Carlo simulations. However, in this model, the order-disorder phase transition is well defined in this system. We have obtained a first-order phase transition for values of connectivity m = 2 and m = 7 of the directed Barabási–Albert network.

scholarly journals A First Order Phase Transition Studied by an Ising-Like Model Solved by Entropic Sampling Monte Carlo Method

Symmetry ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 587
Author(s):  
Jorge Linares ◽  
Catherine Cazelles ◽  
Pierre-Richard Dahoo ◽  
Kamel Boukheddaden
Keyword(s):  
Phase Transition ◽  
Monte Carlo ◽  
Order Phase Transition ◽  
Thermal Hysteresis ◽  
Surface Effects ◽  
Gradual Transition ◽  
First Order ◽  
First Order Phase Transition ◽  
Entropic Sampling ◽  
First Order Phase

Two-dimensional (2D) square, rectangular and hexagonal lattices and 3D parallelepipedic lattices of spin crossover (SCO) compounds which represent typical examples of first order phase transitions compounds are studied in terms of their size, shape and model through an Ising-like Hamiltonian in which the fictitious spin states are coupled via the respective short and long-range interaction parameters J, and G. Furthermore, an environmental L parameter accounting for surface effects is also introduced. The wealth of SCO transition properties between its bi-stable low spin (LS) and high spin (HS) states are simulated using Monte Carlo Entropic Sampling (MCES) method which favors the scanning of macro states of weak probability occurrences. For given J and G, the focus is on surface effects through parameter L. It is shown that the combined first-order phase transition effects of the parameters of the Hamiltonian can be highlighted through two typical temperatures, TO.D., the critical order-disorder temperature and Teq the equilibrium temperature that is fixed at zero effective ligand field. The relative positions of TO.D. and Teq control the nature of the transition and mediate the width and position of the thermal hysteresis curves with size and shape. When surface effects are negligible (L = 0), the equilibrium transition temperature, Teq. becomes constant, while the thermal hysteresis’ width increases with size. When surface effects are considered, L ≠ 0, Teq. increases with size and the first order transition vanishes in favor of a gradual transition until reaching a threshold size, below which a reentrance phenomenon occurs and the thermal hysteresis reappears again, as shown for hexagonal configuration.

scholarly journals Gravitational wave signals of dark matter freeze-out

2021 ◽  
Vol 2021 (2) ◽  
Author(s):  
Danny Marfatia ◽  
Po-Yan Tseng
Keyword(s):  
Phase Transition ◽  
Dark Matter ◽  
Gravitational Waves ◽  
Order Phase Transition ◽  
First Order ◽  
Stochastic Background ◽  
First Order Phase Transition ◽  
Relic Abundance ◽  
First Order Phase ◽  
Freeze Out

Abstract We study the stochastic background of gravitational waves which accompany the sudden freeze-out of dark matter triggered by a cosmological first order phase transition that endows dark matter with mass. We consider models that produce the measured dark matter relic abundance via (1) bubble filtering, and (2) inflation and reheating, and show that gravitational waves from these mechanisms are detectable at future interferometers.

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