Searcharxiv⌕ Search

arXiv subjects

F. Despa

Publications and source records attributed to F. Despa.

5 recordsLinked to original sources
arXiv2001

Relaxation dynamics in the presence of unequally spaced attractors along the reaction coordinate

We show how reaction coordinate path lengths affect the relaxation efficiency of a complex system. To this purpose, we consider the metric contributions to the transition rates. These metric contributions preserve informations about the geometry change of the system at the barrier crossing and, therefore, are directly related to the path lengths. The output of the present work can lead to identify a way to enrich our knowledge about the ability of the complex systems to relax only to preferential structures.

physics.chem-ph↗
arXiv2001

Visualization of Coulomb Correlations in Finite Metallic Systems

We present an analytic ansatz to find the effective electrostatic potential and Coulomb correlations in multicenter problems, specifically homogeneous and doped clusters of metal atoms. The approach is based on a quasi-classical density-functional treatment. We focus on the interpretive aspect of our findings, particularly on extracting insight regarding the geometric effects of Coulomb correlations for any given spatial disposition of ionic cores. For singly-doped metallic clusters we obtain a direct visualization of the variations of both screening and Coulomb correlations with changes of location of the dopant atom. This analysis provides a way to interpret recent observations of the variability of physical properties of metal clusters with changes of composition and geometry.

physics.chem-ph↗
arXiv1996

On the Imbalance of the Dielectric Constant of the PbLixNb3xZr0.51Ti0.49-4xO3 Compound

In the present paper, the dielectric behaviour of the PbLixNb3xZr0.51Ti0.49-4xO3 ( PLNZT) system is analyzed. It is shown that the decrease in the dielectric constant with respect to an increase of the impurity content may be due to an aggregation trend of the interacting off-centre dipoles rather than due to cooperative phenomena which renormalizes the dipole moment of the off-centre impurity.

cond-mat.mtrl-sci↗
arXiv1996

On the Particles Transport Between Embedded Clusters

Diffusional interactions within the Ostwald Ripening process are analyzed in the present paper. An {\it off-centre diffusion approach \/} is performed to point out the direct correlation between the size of clusters. Herein the diffusion solution is derived as a function of both the growing and shrinking cluster sizes. Also, it is shown that the frequency transfer of particles between the shrinking cluster and the growing one may acquire high values due to the medium polarization. As a result, the temporal power law of the cluster growth derived in this theoretical model differs from that predicted by the {\it LSW \/} theory. Experimental data for $Ag$ clusters embedded in a $KCl$ matrix are analyzed both by the present theory and by the $LSW$ theory.

cond-mat↗