Sonoluminescence is the phenomena of light emission from a collapsing gasbubble in a liquid. Theoretical explanations of this extreme energy focusingare controversial and difficult to validate experimentally. We propose to usemolecular dynamics simulations of the collapsing gas bubble to clarify theenergy focusing mechanism, and provide insight into the mechanism of lightemission.  In this paper, we model the interior of a collapsing noble gas bubble as ahard sphere gas driven by a spherical piston boundary moving according to theRayleigh-Plesset equation. We also include a simple treatment of ionizationeffects in the gas at high temperatures. By using fast, tree-based algorithms,we can exactly follow the dynamics of million particle systems during thecollapse. Our results clearly show strong energy focusing within the bubble,including the formation of shocks, strong ionization, and temperatures in therange of 50,000---500,000 degrees Kelvin. Our calculations show that thegas-liquid boundary interaction has a strong effect on the internal gasdynamics. We also estimate the duration of the light pulse from our model,which predicts that it scales linearly with the ambient bubble radius.  As the number of particles in a physical sonoluminescing bubble is within theforeseeable capability of molecular dynamics simulations we also propose thatfine scale sonoluminescence experiments can be viewed as excellent testproblems for advancing the art of molecular dynamics.

Molecular Dynamics Simulation of Sonoluminescence: Modeling, Algorithms and Simulation Results