Temperature and particle concentration dependent effective potential in a bi-dimensional nonvibrating granular model for a glass-forming liquid.

We present an experimental study of effective potential for several particle concentration cases in a bi-dimensional granular model of a glass-forming liquid during cooling. From particle positions, we obtained the radial distribution function and then based on it, the effective potential for the interparticle interaction is extracted via the Ornstein–Zernike equation using Percus–Yevick, hypernetted chain, and Rogers–Young closure relations. We note that the effective potential obtained via the Percus–Yevick approach is the one that best describes our system. The resulting effective potential shows how the spatial correlation increases, as observed through the formation of attractive wells while, the temperature decreases. In cases of high particle concentration close to the glass transition, we observed that several attractive wells appear in the effective potential curve. Under these conditions, particles are arrested by neighboring particles but retain enough kinetic energy to interact at long distances and produce structural changes in the system. For cases of low particle concentration, the changes in the effective potential as the system cools are very small. • Effective potential evolves from repulsive to attractive as temperature decreases. • Structures present higher local order as particle concentration increases. • The Perkus–Yevick approach describes better the physical behavior of the system. • Near glass transition temperature effective potential attractive wells are deeper. • As the temperature diminishes a well first appears and then goes deeper. [ABSTRACT FROM AUTHOR]