We report here on the observation of dislocation nucleation and glide in silicon nanoparticles, after phase transformation from diamond cubic to b-tin crystal structure, within the formed b-tin metallic phase region in atomistic simulations of indentation. The simulation results provide an explanation of the super-high hardness of silicon nanoparticles measured in experiments. By comparing the simulation results with experimental measurement of hardness, we are able to evaluate the performance of two widely used interatomic potential functions: Stillinger-Weber and Tersoff potentials. Through simulations, we have found a critical size of silicon nanoparticles where there is a change in deformation mechanisms, strength, and hardness. The effect of the applied strain rate on simulation results is also investigated.

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