In this paper, we report our study on the minimised atomistic model (MAM) and the determination of an evolution path for dominant B _m I _n clusters during boron diffusion in kinetic Monte Carlo (KMC). It has been known that clusters generated after ion implantation play a decisive role in the enhanced boron diffusion at the tail region while being immobile at the peak region. Our MAM, based on the simple continuum model and the simple atomistic model, takes the smallest number of intermediate clusters into account as well as dominant clusters for the evolution path of interstitial clusters during boron diffusion. We find that intermediate clusters such as B₂I₃ and B₃I₃ play a significant role during the evolution of clusters despite the fact that the lifetimes of the corresponding intermediate clusters are relatively short due to low binding energies. Also, through our simulation results, we find the main evolution path of dominant clusters from B₂I to B₃I during thermal annealing in the MAM. Furthermore, our investigation reveals that the density of BI₂ clusters increases at the beginning of the annealing process while the density of B₃I increases at a later stage. KMC simulation results are compared with experimental SIMS data, which support our theoretical model.