Structure and stability of small compact self-interstitial clusters in crystalline silicon

We have determined the atomic structure and formation energies of small, compact self-interstitial clusters (In, n≤10) in Si using a combination of Metropolis Monte Carlo, tight binding molecular dynamics, and density functional theory calculations. We present predicted local-minimum configurations for compact self-interstitial clusters with n=5-10, together with well-defined smaller clusters (n≤4) for comparison. The cluster formation energies per interstitial exhibit strong minima at n=4 and 8.