Figure 2

(a) Calculated formation energy per atom (Ef, eV atom−1) as a function of the n/(m + n) ratio in the optimized boron–carbon clusters CmBn and (b) cohesive energy per atom (Ec, eV atom−1) of the optimized core–shell boron clusters Bn (n = 110–192) as a function of the cluster size (n) at PBE0/6-311G(d).