title: Solid-state phase transition induced by pressure in LiOH x H2O.
abstract: When the free energy surface of the lithium hydroxide monohydrate crystal was explored, the high-pressure solid-state phase transition was determined. The high-pressure phase has been obtained through ab initio Car-Parrinello molecular dynamics simulation in the isothermic-isobaric ensemble. The recent metadynamics method has been applied to overcome the high activation energy barriers typical of rare events, like solid-state phase transition at high pressures. In the LiOH x H2O system, there are two kinds of H bonds: water-water and hydroxyl-water. The effect of the pressure has been investigated, to give further insight into the high-pressure phase. The strengthening of the H bonds of the system produces modifications in the water and the hydroxyl ion dipole electronic environment. The infrared spectra of both phases have been calculated and compared with experiments, and the assignment of the external modes has been discussed.
authors.affiliation: Laboratorio di Spettroscopia Molecolare, Dipartimento di Chimica, Università di Firenze, Via della Lastruccia 3, 50019 Sesto Fiorentino, Firenze, Italia.
authors.forename: Elisa
authors.initials: E
authors.lastname: Di Pietro
authors.forename: Marco
authors.initials: M
authors.lastname: Pagliai
authors.forename: Gianni
authors.initials: G
authors.lastname: Cardini
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Schettino
mesh_terms: D018020:Lithium Compounds / Q000737:chemistry*; D008958:Models, Molecular; D015394:Molecular Structure; D011312:Pressure; D013055:Spectrophotometry, Infrared; D014867:Water / Q000737:chemistry*
chemical_list: D018020:Lithium Compounds; D014867:Water; C028467:lithium hydroxide