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Landau theory

About: Landau theory is a research topic. Over the lifetime, 2882 publications have been published within this topic receiving 57078 citations.


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TL;DR: A phase diagram for the shear flow of dry granular particles in two dimensions based on simulations and a phenomenological Landau theory for a nonequilibrium first-order phase transition is proposed that incorporates both frictional as well as frictionless particles.
Abstract: We propose a phase diagram for the shear flow of dry granular particles in two dimensions based on simulations and a phenomenological Landau theory for a nonequilibrium first-order phase transition. Our approach incorporates both frictional as well as frictionless particles. The most important feature of the frictional phase diagram is reentrant flow and a critical jamming point at finite stress. In the frictionless limit the regime of reentrance vanishes and the jamming transition is continuous with a critical point at zero stress. The jamming phase diagrams derived from the model agree with the experiments of Bi et al. [Nature (London) 480, 355 (2011)] and brings together previously conflicting numerical results.

45 citations

Journal ArticleDOI
TL;DR: In this article, conditions for single phase and multiphase equilibria are studied using Flory-Huggins free energy of mixing with χ representing the A-B interaction parameter.
Abstract: Ideal random AB copolymers with degree of polymerization N are mixtures of N+1 types of chains with different compositions (fractions fi of A monomers). Conditions for single phase and multiphase equilibria are studied using Flory–Huggins free energy of mixing with χ representing the A–B interaction parameter. The spinodal for one phase instability is given by χs=[2f(1−f)]−1 for all N, where f is the average A fraction in the system. The transition from one to two phases is continuous at χ=χs when f=0.5 and discontinuous at χ≤χs when f≠0.5. Three, four, and more phases become stable at larger values of χ. Our numerical solution suggests that the stability range for multiple phases approaches Δχ≊0.15 at large (but finite) N. Macroscopically and microscopically phase separated states are investigated with the Landau approach of Fredrickson, Milner and Leibler. The Landau method gives reasonable but inexact results for two macroscopic phases when the random copolymer has compositional symmetry (f=0.5). A dis...

45 citations

Journal ArticleDOI
TL;DR: In this article, the authors used the symmetric group S Q symmetry of the Q-state Potts model to classify the (scalar) operator content of its underlying field theory in arbitrary dimension.

45 citations

Journal ArticleDOI
TL;DR: In this paper, Monte Carlo simulations were carried out to investigate the effect of molecular shape on liquid-crystal order, where each model mesogen consists of several soft spheres bonded rigidly together.
Abstract: We carry out Monte Carlo simulations to investigate the effect of molecular shape on liquid-crystal order. In our approach, each model mesogen consists of several soft spheres bonded rigidly together. The arrangement of the spheres may be straight (to represent uniaxial molecules), Z-shaped (for biaxial molecules), or banana-shaped (for bent-core molecules). Using this approach, we investigate the alignment of the nematic phase by substrates decorated with parallel ridges. We compare results for wide and narrow ridge spacing and examine local order near the substrates, and show that our results are consistent with the predictions of Landau theory. We also investigate chiral symmetry-breaking in systems of bent-core molecules. We find a chiral crystalline phase as well as a nonchiral smectic-A phase, but not a chiral smectic-C phase.

44 citations

Journal ArticleDOI
TL;DR: In this article, the authors discuss the 2PPI expansion, which sums bubble graphs to all orders, in the context of SU(N) Yang-Mills theory in the Landau gauge, and investigate the possible existence of a gluon condensate of mass dimension two,, and the corresponding nonzero vacuum energy.

44 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202317
202242
202142
202041
201949
201855