title: Hydrogen divacancy diffusion: a new perspective on H migration in MgH2materials for energy storage.
abstract: The formation and diffusion of pairs of hydrogen vacancies (divacancies) in magnesium hydride is modeled using density functional theory. Compared to the commonly studied case of single hydrogen vacancies, it is found that divacancies are energetically favored over two isolated vacancies. Also, as a function of the diffusion axis considered, the calculated diffusion barriers of divacancies are either smaller or of comparable magnitude with respect to the diffusion barriers of a single vacancy. These findings shed new light on hydrogen transport in MgH2, which is of crucial importance to understand the kinetics of hydrogen take-up and release in this storage material.
authors.affiliation: Departamento de Física, Universidad Nacional del Sur & IFISUR (UNS-CONICET), Av. Alem 1253, 8000, Bahía Blanca, Argentina. egerman@uns.edu.ar and The Abdus Salam International Center for Theoretical Physics (ICTP), Strada Costiera 11, 34151, Trieste, Italy.
authors.forename: Estefania
authors.identifier: http://orcid.org/0000-0002-0312-8929
authors.initials: E
authors.lastname: German
authors.affiliation: The Abdus Salam International Center for Theoretical Physics (ICTP), Strada Costiera 11, 34151, Trieste, Italy.
authors.forename: Ralph
authors.initials: R
authors.lastname: Gebauer