arXiv subjects

Arūnas Radzvilavičius

Publications and source records attributed to Arūnas Radzvilavičius.

3 recordsLinked to original sources

arXiv2012

Geometrical defects in two-dimensional melting of many-particle Yukawa systems

We perform Langevin dynamics simulations and use polygon construction method to investigate two-dimensional (2D) melting and freezing transitions in many-particle Yukawa systems. 2D melting transitions can be characterized as proliferation of geometrical defects - non-triangular polygons, obtained by removing unusually long bonds in the triangulation of particle positions. A 2D liquid is characterized by the temperature-independent number of quadrilaterals and linearly increasing number of pentagons. We analyze specific types of vertices, classified by the type and distribution of polygons surrounding them, and determine temperature dependencies of their concentrations. Critical points in a solid-liquid transition are followed by the peaks in the abundances of certain types of vertices.

physics.plasm-ph↗

arXiv2012

Dimensional transitions in small Yukawa clusters

We provide the detailed analysis of structural transitions leading to the rapid changes in dimensionality of small Yukawa clusters. These transformations are induced by the variations in the shape of confinement as well as the screening strength. We show, that even in the most primitive systems composed of only a few strongly interacting particles, the order parameter exhibits a power-law behavior in the vicinity of the critical point of the continuous transition. The critical exponent γ=1/2 is found to be universal in all studied cases, which is consistent with the general theory of continuous phase transitions.

cond-mat.stat-mech↗

arXiv2012

Configurational entropy of Wigner crystals

We present a theoretical study of classical Wigner crystals in two- and three-dimensional isotropic parabolic traps aiming at understanding and quantifying the configurational uncertainty due to the presence of multiple stable configurations. Strongly interacting systems of classical charged particles confined in traps are known to form regular structures. The number of distinct arrangements grows very rapidly with the number of particles, many of these arrangements have quite low occurrence probabilities and often the lowest-energy structure is not the most probable one. We perform numerical simulations on systems containing up to 100 particles interacting through Coulomb and Yukawa forces, and show that the total number of metastable configurations is not a well defined and representative quantity. Instead, we propose to rely on the configurational entropy as a robust and objective measure of uncertainty. The configurational entropy can be understood as the logarithm of the effective number of states; it is insensitive to the presence of overlooked low-probability states and can be reliably determined even within a limited time of a simulation or an experiment.

physics.plasm-ph↗