Realistic Implementation of the Particle Model for the Visualization of Nanoparticle Precipitation and Growth

An application for visualizing the aggregation of structureless atoms is presented. The application allows us to demonstrate on a qualitative basis, as well as by quantitatively monitoring the aggregate surface/volume ratio, that the enhanced reactivity of nanoparticles can be connected with their large specific surface. It is suggested that, along with the use of geometric analogies, this bottom-up approach can be effective in discussing the enhanced reactivity proprieties of nanoparticles. The application is based on a two-dimensional realistic dynamic model where atoms move because of their thermal and interaction potential energies, and the trajectories are determined by solving numerically Newton’s laws according to a Molecular Dynamics (MD) scheme. For this purpose, a web-based MD engine was adapted as needed. It is suggested that, when possible, using a realistic simulation rather than simple animations offers several advantages in the visualization of processes of interest in chemistry education. First, in a simulation the outcome of the process under study is not set a priori but it is the result of the dynamic evolution of the system; furthermore, specific parameters can be systematically varied, and the effects of these changes can be investigated. The application can be used at different levels of detail and in different instruction levels. Qualitative visual observations of the growing aggregates and of the progressive decrease of the reactive surface are suitable at all levels of instruction. Systematic investigations on the effect of changes of the atomic and aggregate sizes and temperature, suitable for senior high school and college courses, are also reported.