We present results of ab initio calculations for the structure and energeti
cs of boron-interstitial clusters in Si and a respective continuum model fo
r the nucleation, growth, and dissolution of such clusters. The structure o
f the clusters and their possible relationship to boron precipitates and in
terstitial-cluster formation are discussed. We find that neither the local-
density approximation nor the generalized-gradient approximation to the den
sity-functional theory result in energetics that predict annealing and acti
vation experiments perfectly well. However, gentle refitting of the numbers
results in a model with good predictive qualities. (C) 2000 American Insti
tute of Physics. [S0003- 6951(00)04539-3].