Abstract
Nucleation phenomena are ubiquitous in nature and the presence of impurities in every real and experimental system is unavoidable. Yet numerical studies of nucleation are nearly always conducted for entirely pure systems. We have studied the behaviour of the droplet free energy in two dimensional Ising model in the presence of randomly positioned static and dynamic impurities. We have shown that both the free energy barrier height and critical nucleus size monotonically decreases with increasing the impurity density for the static case. We have compared the nucleation rates obtained from the Classical Nucleation Theory and the Forward Flux Sampling method for different densities of the static impurities. The results show good agreement. In the case of dynamic impurities, we observe preferential occupancy of the impurities at the boundary positions of the nucleus when the temperature is low. This further boosts enhancement of the nucleation rate due to lowering of the effective interfacial free energy.
Highlights
Nucleation phenomena are of great importance both in physics and chemistry
Impurities, the average impurity density per unit length of cluster circumference is independent of both temperature and cluster size, and we can capture their impact on the interfacial free energy via this simple functional form
We have studied nucleation rates in the two dimensional Ising model in the presence of randomly placed impurities on a square lattice using two independent methods which are BD theory and Forward flux sampling (FFS)
Summary
Nucleation phenomena are of great importance both in physics and chemistry. The study of nucleation has a long history, rooted in the widely used theoretical model of classical nucleation theory (CNT)[1] and the Becker–Doring (BD) expression for the nucleation rate.[2]. We have shown that the impurity particles preferentially occupy the boundary positions of the nucleus for the dynamic case when the temperature is low This surface accumulation process enhances the nucleation rate by a multiple of 104 compared to the static case. We describe in more detail the simulation techniques used to calculate the barrier heights and the nucleation rates
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call