PubMed Health⌕ Search

Biomedical subjects

S Tarafdar

Publications and source records attributed to S Tarafdar.

6 recordsLinked to original sources

Percolation in models of thin film depositions.

We have studied the percolation behavior of deposits for different (2+1)-dimensional models of surface layer formation. The mixed model of deposition was used, where particles were deposited selectively according to the random (RD) and ballistic (BD) deposition rules. In the mixed one-component models with deposition of only conducting particles, the mean height of the percolation layer (measured in monolayers) grows continuously from 0.898 32 for the pure RD model to 2.605 for the pure BD model, but the percolation transition belongs to the same universality class, as in the two-dimensional (2D) random percolation problem. In two-component models with deposition of conducting and isolating particles, the percolation layer height approaches infinity as concentration of the isolating particles becomes higher than some critical value. The crossover transition from 2D to 3D percolation was observed with increase of the percolation layer height.

Journal Article↗

Condensation and evaporation on a randomly occupied square lattice.

We study the evolution of an initially random distribution of particles on a square lattice, under certain rules for "growing" and "culling" of particles. In one version we allow the particles to move laterally along the surface (mobile layer) and in the other version this motion is not allowed (immobile case). In the former case, both analytical and computer simulation results are presented, while in the latter only simulation is possible. We introduce growth and culling probabilities appropriate for condensation and evaporation on a two-dimensional surface, and compare results with existing models for this problem. Our results show a very interesting behavior under certain conditions that are quite different from earlier models. We find a possibility of hysteresis not reported earlier for such models.

Journal Article↗

Diffusion with rearranging traps.

A model for diffusion on a cubic lattice with a random distribution of traps is developed. The traps are redistributed at certain time intervals. Such models are useful for describing systems showing dynamic disorder, such as ion-conducting polymers. In the present model the traps are infinite, unlike an earlier version with finite traps. For the infinite trap version a simple analytical calculation is possible and the results agree qualitatively with simulations.

Journal Article↗