title: Ab initio molecular dynamics study of a mixture of HF(aq) and HCl(aq).
abstract: We have studied a mixture of HF and HCl molecules in water using Car-Parrinello ab initio molecular dynamics (CPMD). We have done simulations with 1 HF and 3 HCl molecules, 3 HF and 4 HCl, 6 HF and 8 HCl (6/8 simulation), and 14 HF molecules. All simulations consist of 32 molecules, and they were 10-96 ps long. The HF dissociation probability was around 30%, and HCl's was more than 90%. The solvation of the HF molecule was much better than the solvation of HCl. The solvation environment of F, both the F- ion and the F in HF, did not depend much on the acids concentration, whereas the Cl coordination numbers were rather sensitive to the concentration. In the 6/8 simulation, all XH-Y (X, Y = F, Cl) type molecules were observed and the FH-F was the most probable. In general, the molecular structures in mixed aqueous acid systems were similar to the pure HF(aq) and HCl(aq) systems.
authors.affiliation: Department of Chemistry, University of Oulu, P.O. Box 3000, 90014 Oulu, Finland. kari.laasonen@oulu.fi
authors.forename: Kari
authors.initials: K
authors.lastname: Laasonen
authors.forename: Julen
authors.initials: J
authors.lastname: Larrucea
authors.forename: Atte
authors.initials: A
authors.lastname: Sillapää