Nature of segregation of reactants in diffusion controlled A+B reactions: Role of mobility in forming compact clusters

TL;DR

This study uses Monte-Carlo simulations to explore how unequal mobilities of reactants affect segregation patterns and cluster structures in diffusion-controlled A+B reactions, revealing asymmetric density fluctuations and distinct clustering behaviors.

Contribution

It provides the first detailed explanation of how asymmetric mobilities influence segregation mechanisms and cluster compactness in low-dimensional A+B reaction systems.

Findings

Mobile species form homogeneous, random clusters.

Less mobile species form compact, spatially restricted clusters.

Asymmetric mobilities lead to asymmetric density fluctuations.

Abstract

We investigate the A+B=0 bimolecular chemical reaction taking place in low-dimensional spaces when the mobilities of the two reacting species are not equal. While the case of different reactant mobilities has been previously reported as not affecting the scaling of the reactant densities with time, but only the pre-exponential factor, the mechanism for this had not been explained before. By using Monte-Carlo simulations we show that the nature of segregation is very different when compared to the normal case of equal reactant mobilities. The clusters of the mobile species are statistically homogeneous and randomly distributed in space, but the clusters of the less mobile species are much more compact and restricted in space. Due to the asymmetric mobilities, the initial symmetric random density fluctuations in time turn into asymmetric density fluctuations. We explain this trend by calculating the correlation functions for the positions of particles for the several different cases.