arXiv subjects

Itay Azizi

Publications and source records attributed to Itay Azizi.

6 recordsLinked to original sources

arXiv2026

Multiple pattern formation in quorum sensing of density enhanced motility

Using Langevin dynamics simulations, I investigate nonequilibrium systems of particles following a density-enhanced motility (DEM) rule: particles are passive below a critical local density and active above it. This mechanism represents an inverse of the conventional quorum-sensing rule. I explore specifically quorums much larger than particle size and at two levels of activity. Above critical values of the density, quorum size, and activity, the system undergoes phase separation into low- and high-energy regions. The passive particles organize into distinct spatial patterns, including holes, stripes, and labyrinthine structures, while the active particles form a gas. I characterize the resulting steady states and identify the qualitative mechanisms governing the selection of different morphological regimes. I further discuss the relevance of these results to biological systems governed by analogous quorum-sensing mechanisms and to biological systems exhibiting related forms of spatial organization. Finally, I present directions for future investigation.

cond-mat.soft↗

arXiv2026

Correlated and anti-correlated density dependent motility

I study via Langevin dynamics simulations two opposite cases of systems of particles that alternate their identity according to density dependent motility (DDM) rules and interact via a soft repulsive potential. In the correlated case, dilute regions are passive and dense regions are active, while in the anti-correlated case, dilute regions are active and dense regions are passive. I classify the emerging steady states, explain the principal phase transitions, and finally suggest directions for further investigation.

cond-mat.soft↗

arXiv2024

Shape, temperature and density interplay in depletion forces

Via numerical simulations and analytical calculations, depletion forces are studied in mixtures of small and big particles that interact via soft repulsive potentials. While big particles are spherical, small particles are nonspherical with shapes that vary gradually, from squares to rods via intermediate shapes. The mixtures are studied for a wide range of densities and temperature. Depletion forces and their resulting potentials depend on the interplay of shape, temperature and density, an argument that is elaborated qualitatively and quantitatively. While in some thermodynamic conditions, depletion potentials of distinct shapes are distinguishable, in different conditions, they are very similar. Finally, I propose novel computational models and experiments for further investigation of the effect of morphology on phase separation in and out of thermal equilibrium.

cond-mat.soft↗

arXiv2021

Reentrant Transitions in a Mixture of Small and Big Particles Interacting via Soft Repulsive Potential

We report the first observation of temperature-controlled reentrant transition in simulations of mixtures of small and big particles interacting via soft repulsive potential in 2D. As temperature increases, the system passes from a fluid mixture, to a crystal of big particles in a fluid of small particles and back to a fluid mixture. Solidification is driven by entropy gain of small particles which overcomes the free energy cost of confining big ones. Melting results from enhanced interpenetration of particles at high temperature which reduces the entropic forces that stabilize the crystal.

cond-mat.soft↗

arXiv2020

Systems with size and energy polydispersity: from glasses to mosaic crystals

We use Langevin dynamics simulations to study dense 2d systems of particles with both size and energy polydispersity. We compare two types of bidisperse systems which differ in the correlation between particle size and interaction parameters: in one system big particles have high interaction parameters and small particles have low interaction parameters, while in the other system the situation is reversed. We study the different phases of the two systems and compare them to those of a system with size but not energy bidispersity. We show that, depending on the strength of interaction between big and small particles, cooling to low temperatures yields either homogeneous glasses or mosaic crystals.

cond-mat.soft↗

arXiv2018

Identity Ordering and Metastable Clusters in Fluids with Random Interactions

We use Langevin dynamics simulations to study dense two-dimensional systems of particles where all binary interactions are different (AID) in the sense that each interaction parameter is characterized by a randomly chosen number. We compare two systems that differ by the probability distributions from which the interaction parameters are drawn: uniform (U) and exponential (E). Both systems undergo neighborhood identity ordering (NIO) and form metastable clusters in the fluid phase near the liquid-solid transition but the effects are much stronger in E than in U systems. Possible implications of our results for the control of the structure of multicomponent alloys are discussed.

cond-mat.soft↗