arXiv subjects

Stoyan Pisov

Publications and source records attributed to Stoyan Pisov.

3 recordsLinked to original sources

arXiv2017

A model provides insight into electric field-induced rupture mechanism of water-in-toluene emulsion films

This paper presents the first MD simulations of a model, which we have designed for understanding the development of electro-induced instability of a thin toluene emulsion film in contact with saline aqueous phase. This study demonstrates the charge accumulation role in toluene film rupture when a DC electric field is applied. The critical value of the external field at which film ruptures, thin film charge distribution, capacitance, number densities and film structure have been obtained in simulating the system within NVT and NPT ensembles. A mechanism of thin film rupture driven by the electric discharge is suggested.We show that NPT ensemble with a constant surface tension is a better choice for further modeling of the systems that resemble more close the real films.

physics.chem-ph↗

arXiv2007

Gold Clusters Sliding on Graphite: a Possible Quartz Crystal Microbalance Experiment?

A large measured 2D diffusion coefficient of gold nanoclusters on graphite has been known experimentally and theoretically for about a decade. When subjected to a lateral force, these clusters should slide with an amount of friction that could be measured. We examine the hypothetical possibility to measure by Quartz Crystal Microbalance (QCM) the phononic sliding friction of gold clusters in the size range around 250 atoms on a graphite substrate between 300 and 600 K. Assuming the validity of Einstein's relations of ordinary Brownian motion and making use of the experimentally available activated behavior of the diffusion coefficients, we can predict the sliding friction and slip times as a function of temperature. It is found that a prototypical deposited gold cluster could yield slip times in the standard measurable size of 10^(-9) sec for temperatures around 450-500 K, or 200 C. Since gold nanoclusters may also melt around these temperatures, QCM would offer the additional chance to observe this phenomenon through a frictional change.

cond-mat.mtrl-sci↗

arXiv2002

Optimization of molecular clusters configurations using a Genetic Algorithm

We present a genetic algorithm developed (GA) to optimize molecular AF_6 cluster configurations with respect to their energy. The method is based on the Darvin's evolutionary theory: structures with lowest energies survive in a system of fixed number of clusters. Two existing structures from a given population are combined in a special way to produce a new structure (child) which is kept if its energy is lower than the highest energy in the ensemble. To keep the population constant we reject the structure with the highest energy. This algorithm gives a better result than the optimization techniques used previously. Using the GA we have found a new structure corresponding to the (seemingly) global minimum. The most important result is that the new structure is detected only if the molecular cluster contains more than a critical number of molecules.

physics.atm-clus↗