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I Ispolatov

Publications and source records attributed to I Ispolatov.

9 recordsLinked to original sources
PubMed2002

Phase diagram of self-attracting systems.

A phase diagram of microcanonical ensembles of self-attracting particles is studied for two types of short-range potential regularizations: self-gravitating fermions and classical particles interacting via an attractive soft -(r(2)+r(2)(0))(-1/2) Coulomb potential. When the range of regularization is sufficiently short, the self-attracting systems exhibit gravitational or collapselike transition. As the fermionic degeneracy or the softness radius increases, the gravitational phase transition crosses over to a normal first-order phase transition, becomes second-order at a critical point, and finally disappears. Applicability of a commonly used saddle-point or mean-field approximation and importance of metastable states is discussed.

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PubMed2001

Collapse in systems with attractive nonintegrable potentials.

Collapse, or a gravitational-like phase transition, is found in microcanonical ensembles of particles with an attractive 1/r(alpha) potential not only for alpha = 1 but for all 0<alpha<3. The phase behavior of the system is complex: If an effective sufficiently short-range cutoff is applied, the density of the collapsed phase is finite everywhere; if not, the collapse results in a density singularity. Also, with increasing effective cutoff range, the gravitational phase transition will cross over to a normal first-order phase transition.

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PubMed2001

Phase transitions in systems with 1/r(alpha) attractive interactions.

Collapse, or a gravitational-like phase transition is studied in a microcanonical ensemble of particles with an attractive 1/r(alpha) potential. A mean-field continuous integral equation is used to determine a saddle-point density profile that extremizes the entropy functional. For all 0 < alpha < 3, a critical energy is determined below which the entropy of the system exhibits a discontinuous jump. If an effective short-range cutoff is applied, the entropy jump is finite; if not, the entropy diverges to +infinity. A stable integral equation solution represents a state with maximal entropy; the reverse is always true only for a modified integral equation introduced here.

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PubMed2000

Phase transition in a traffic model with passing

We investigate a traffic model in which cars either move freely with quenched intrinsic velocities or belong to clusters formed behind slower cars. In each cluster, the next-to-leading car is allowed to pass and resume free motion. The model undergoes a phase transition from a disordered phase for the high passing rate to a jammed phase for the low rate. In the disordered phase, the cluster size distribution decays exponentially in the large size limit. In the jammed phase, the distribution of finite clusters is independent on the passing rate, but it accounts only for a fraction of all cars; the "excessive" cars form an infinite cluster moving with the smallest velocity. Mean-field equations, describing the model in the framework of Maxwell approximation, correctly predict the existence of phase transition and adequately describe the disordered phase; properties of the jammed phase are studied numerically.

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PubMed1999

Persistence in systems with algebraic interaction.

Persistence in coarsening one-dimensional spin systems with a power-law interaction r(-1-sigma) is considered. Numerical studies indicate that for sufficiently large values of the interaction exponent sigma (sigma > or =1/2 in our simulations), persistence decays as an algebraic function of the length scale L, P(L) approximately L(-theta). The persistence exponent theta is found to be independent on the force exponent sigma and close to its value for the extremal (sigma-->infinity) model, theta =0.175 075 88. For smaller values of the force exponent (sigma < 1/2), finite size effects prevent the system from reaching the asymptotic regime. Scaling arguments suggest that in order to avoid significant boundary effects for small sigma, the system size should grow as [O(1/sigma)](1/sigma).

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