On the freezing and structure of hard spheres under spherical confinement

Abstract

The equation of state and the structure of hard spheres confined in spherical pores have been investigated via molecular dynamics for different pore radii ranging from 5.0 to 10.0 σ, where σ is the particle diameter. The hard boundary is chosen to capture the pure geometric effect of spherical confinement. A discontinuity in the equation of state was observed, indicating the onset of a freezing-like phase transition, which was similar to that of the bulk hard-sphere fluids. The behaviour of confined particles resembles that of the bulk with increase in the pore size, while its deviation from the bulk is found to be larger at the solid-like phase. For the pore radius below 5.0, FCC-like crystal clusters are not formed in spherically confined hard spheres.

Keywords:

• spherical pore
• confined hard spheres
• phase transition
• freezing
• molecular dynamics

Acknowledgements

Dr Kwak acknowledges the financial support by a grant from Creative and Innovation Project (no. 1.120026.01) at the UNIST (Ulsan National Institute of Science and Technology). Computational resources have been provided by the high-performance computing centre of Nanyang Technological University, Singapore.