Br-2(X)Microsolvation in helium clusters: Effect of the interaction on quantum solvent density distribution

The Born-Oppenheimer potential energy surface for the Br-2(X) molecule interacting with a varying number of He-4 bosons is constructed following two different schemes which employ either a full ab initio evaluation of the Br-2-He interaction forces or an estimate of the latter through an empirical model. Both descriptions are employed by carrying out diffusion Monte Carlo (DMC) calculations of the ground-state energies and quantum wave-functions for Br-2-(He)n clusters with n up to 24. The results clearly indicate, for both interactions, the occurrence of the full solvation of the molecular dopant within the quantum bosonic "solvent" but also show differences between the two models in terms of the expected density distributions of the surrounding particles within the shorter-range region that makes up the clusters with smaller n values. Our calculations also show that such differences become insignificant for the larger He-4 clusters surrounding the Br-2 molecule, where density profiles and bulk behaviour are chiefly driven by the solvent structure, once n values reach the region of 15-20 adatoms.