Br2(X) Microsolvation in Helium Clusters: Effect of the Interaction on the Quantum Solvent Density Distribution

• Published in: Chemphyschem 2005-07, Vol.6 (7), p.1348-1356
• Main Authors: Di Paola, Cono, Gianturco, Franco A., López-Durán, David, de Lara-Castells, Maria Pilar, Delgado-Barrio, Gerardo, Villarreal, Pablo, Jellinek, Julius
• Format: Article
• Language: English
• Subjects: ab initio calculations; bromine; cluster compounds; helium; microsolvation
• ISSN: 1439-4235; 1439-7641
• DOI: 10.1002/cphc.200400530

The Born–Oppenheimer potential energy surface for the Br2(X) molecule interacting with a varying number of 4He bosons is constructed following two different schemes which employ either a full ab initio evaluation of the Br2–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 wavefunctions for Br2–(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 4He clusters surrounding the Br2 molecule, where density profiles and bulk behaviour are chiefly driven by the solvent structure, once n values reach the region of 15–20 adatoms. Studies on molecular clusters: The Born–Oppenheimer potential energy surface between bromine and a varying number N of 4He bosons is compared using two methods: ab initio evaluation and an empirical estimate (see picture for computed total binding energies Ebin). Diffusion Monte Carlo calculations show full solvation in the helium cluster in both cases, with differences in short‐range density distributions.