title: How Many Water Molecules Does it Take to Dissociate HCl?
abstract: The potential energy surfaces of the HCl(H2O)n (n is the number of water molecules) clusters are systematically explored using density functional theory and high-level ab initio computations. On the basis of electronic energies, the number of water molecules needed for HCl dissociation is four as reported by some experimental groups. However, this number is five owing to the inclusion of entropic factors. Wiberg bond indices are calculated and analyzed, and the results provide a quadratic correlation and classification of clusters according to the nondissociated, partially dissociated, and fully dissociated character of the H-Cl bond. Our computations show that if temperature is not controlled during the experiment, the values obtained for the dipole moment (or for any measurable property) are susceptible to change, providing a different picture of the number of water molecules needed for HCl dissociation in a nanoscopic droplet.
authors.affiliation: Departamento de Física Aplicada, Centro de Investigación y de Estudios Avanzados, Unidad Mérida, Km 6 Antigua Carretera a Progreso. Apdo. Postal 73, Cordemex, 97310, Mérida, Yuc., México.
authors.forename: Alba
authors.initials: A
authors.lastname: Vargas-Caamal
authors.affiliation: Departamento de Física Aplicada, Centro de Investigación y de Estudios Avanzados, Unidad Mérida, Km 6 Antigua Carretera a Progreso. Apdo. Postal 73, Cordemex, 97310, Mérida, Yuc., México.
authors.forename: Jose Luis
authors.initials: JL
authors.lastname: Cabellos
authors.affiliation: Instituto Tecnológico Superior de Calkiní, Av. Ah-Canul s/n, Carr. Fed. Calkiní-Campeche, CP, 24900, Calkiní, Campeche, México.
authors.forename: Filiberto
authors.initials: F
authors.lastname: Ortiz-Chi
authors.affiliation: Department of Chemistry, Imperial College London, South Kensington campus, London, SW7 2AZ, UK.
authors.forename: Henry S
authors.initials: HS
authors.lastname: Rzepa
authors.affiliation: Instituto de Química, Universidad de Antioquia UdeA, Calle 70 No. 52-21, Medellín, Colombia. albeiro.restrepo@udea.edu.co.
authors.forename: Albeiro
authors.initials: A
authors.lastname: Restrepo
authors.affiliation: Departamento de Física Aplicada, Centro de Investigación y de Estudios Avanzados, Unidad Mérida, Km 6 Antigua Carretera a Progreso. Apdo. Postal 73, Cordemex, 97310, Mérida, Yuc., México. gmerino@mda.cinvestav.mx.
authors.forename: Gabriel
authors.initials: G
authors.lastname: Merino
keywords: ab initio calculations; dissociation; global optimization; hydrogen bonds; microsolvation