The authors performed systematic ab initio calculations of fluorine clustering in silicon. The calculated formation energies were used to implement a new kinetic Monte Carlo (KMC) model. They present the ab initio results, discuss the new KMC model, and compare the resulting simulated profiles to experimental profiles. The calculated formation energies show clear trends with the number of missing silicon atoms and the number of fluorine atoms. The deduced KMC model based on the ab initio energetics is able to reproduce the reduction in boron transient enhanced diffusion in the presence of fluorine.