Complex network structure of flocks in the Vicsek Model with Vectorial Noise

In the Vicsek Model (VM), self-driven individuals try to adopt the direction of movement of their neighbors under the influence of noise, thus leading to a noise-driven order–disorder phase transition. By implementing the so-called Vectorial Noise (VN) variant of the VM (i.e. the VM-VN model), this phase transition has been shown to be discontinuous (first-order). In this paper, we perform an extensive complex network study of VM-VN flocks and show that their topology can be described as highly clustered, assortative, and nonhierarchical. We also study the behavior of the VM-VN model in the case of "frozen flocks" in which, after the flocks are formed using the full dynamics, particle displacements are suppressed (i.e. only rotations are allowed). Under this kind of restricted dynamics, we show that VM-VN flocks are unable to support the ordered phase. Therefore, we conclude that the particle displacements at every time-step in the VM-VN dynamics are a key element needed to sustain long-range ordering throughout.

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Temperature-triggered order–disorder phase transition in molecular-ionic material N-butyldiethanolammonium picrate monohydrate

RSC Advances ◽

10.1039/c6ra12178k ◽

2016 ◽

Vol 6 (73) ◽

pp. 69546-69550 ◽

Cited By ~ 5

Author(s):

Tariq Khan ◽

Muhammad Adnan Asghar ◽

Zhihua Sun ◽

Chengmin Ji ◽

Lina Li ◽

...

Keyword(s):

Phase Transition ◽

Structural Phase Transition ◽

Structural Phase ◽

Dielectric Materials ◽

Disorder Phase Transition ◽

First Order ◽

Oxygen Atoms

We report an organic–ionic material that undergoes a first-order structural phase transition, induced by order–disorder of oxygen atoms in picrate anion. This strategy offers a potential pathway to explore new switchable dielectric materials.

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Complex Network Structure of Flocks in the Standard Vicsek Model

Journal of Statistical Physics ◽

10.1007/s10955-013-0827-4 ◽

2013 ◽

Vol 153 (2) ◽

pp. 270-288 ◽

Cited By ~ 8

Author(s):

Gabriel Baglietto ◽

Ezequiel V. Albano ◽

Julián Candia

Keyword(s):

Complex Network ◽

Network Structure ◽

Vicsek Model

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A temperature-induced order–disorder phase transition in a 4-substituted 4,2′:6′,4′′-terpyridine

Acta Crystallographica Section B Structural Science Crystal Engineering and Materials ◽

10.1107/s205252061501937x ◽

2015 ◽

Vol 71 (6) ◽

pp. 805-813 ◽

Cited By ~ 1

Author(s):

Juan Granifo ◽

Marleen Westermeyer ◽

Maricel Riquelme ◽

Rubén Gaviño ◽

Sebastián Suárez ◽

...

Keyword(s):

Phase Transition ◽

Single Crystal ◽

Single Molecule ◽

Temperature Phase ◽

Asymmetric Unit ◽

Phase Form ◽

Space Group ◽

Cell Parameters ◽

Disorder Phase Transition ◽

First Order

Crystals of 4′-(isoquinolin-4-yl)-4,2′:6′,4′′-terpyridine (iqtp), C24H16N4, grown from an ethanol solution, undergo a reversible first-order single-crystal to single-crystal phase transition at T c in the range 273–275 K, from a disordered higher-temperature phase [form (I)] in the space group P21/c, with one single molecule in the asymmetric unit, to an ordered lower-temperature one [form (II)] in the space group P21/n, with two independent molecules in the asymmetric unit. There is a group–subgroup relationship linking (I)–(II), due to cell doubling and the disappearance of a number of symmetry operations. In addition to X-ray diffraction, the transition has been monitored by Raman spectroscopy and differential scanning calorimetry, the latter disclosing an enthalpy change of 0.72 (6) kJ mol−1. Variations of the unit-cell parameters with temperature between 170 and 293 K are presented. The evolution of diffraction spots in the vicinity of the transition temperature shows the coexistence of both phases, confirming the first-order character of the transition. Structural details of both phases are analyzed and intermolecular interactions compared in order to investigate the mechanism of the phase transition. A three-dimensional Hirshfeld surface analysis was performed to corroborate the significant changes in the intermolecular features.

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ON THE EMERGENCE OF COLLECTIVE ORDER IN SWARMING SYSTEMS: A RECENT DEBATE

International Journal of Modern Physics B ◽

10.1142/s0217979209053552 ◽

2009 ◽

Vol 23 (18) ◽

pp. 3661-3685 ◽

Cited By ~ 39

Author(s):

M. ALDANA ◽

H. LARRALDE ◽

B. VÁZQUEZ

Keyword(s):

Phase Transition ◽

Boundary Conditions ◽

Numerical Results ◽

Dynamical Phase Transition ◽

Vicsek Model ◽

Numerical Evidence ◽

First Order ◽

Dynamical Phase ◽

Recent Debate ◽

Order Continuous

In this work, we consider the phase transition from ordered to disordered states that occur in the Vicsek model of self-propelled particles. This model was proposed to describe the emergence of collective order in swarming systems. When noise is added to the motion of the particles, the onset of collective order occurs through a dynamical phase transition. Based on their numerical results, Vicsek and his colleagues originally concluded that this phase transition was of second order (continuous). However, recent numerical evidence seems to indicate that the phase transition might be of first order (discontinuous), thus challenging Vicsek's original results. In this work, we review the evidence supporting both aspects of this debate. We also show new numerical results indicating that the apparent discontinuity of the phase transition may in fact be a numerical artifact produced by the artificial periodicity of the boundary conditions.

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FREEDERICKSZ-LIKE TRANSITIONS IN COMPENSATED NEMATIC LIQUID CRYSTALS

International Journal of Modern Physics B ◽

10.1142/s0217979291000390 ◽

1991 ◽

Vol 05 (04) ◽

pp. 697-707

Author(s):

G. BARBERO ◽

L.R. EVANGELISTA ◽

Z. GABBASOVA

Keyword(s):

Phase Transition ◽

Phase Diagram ◽

Liquid Crystals ◽

Relative Phase ◽

Nematic Liquid Crystals ◽

Dielectric Anisotropy ◽

Critical Fields ◽

Inversion Point ◽

Disorder Phase Transition ◽

First Order

The occurrence of the Freedericksz transitions at the inversion point of the main dielectric anisotropy in nematic liquid crystals is discussed. It is shown that, if this kind of order-disorder phase transition can take place, they are always of the first order. The critical fields are evaluated, and the relative phase diagram is discussed.

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

International Journal of Modern Physics C ◽

10.1142/s0129183106009679 ◽

2006 ◽

Vol 17 (09) ◽

pp. 1267-1272 ◽

Cited By ~ 9

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.

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