title: Boroxol Rings in Liquid and Vitreous B2O3 from First Principles.
abstract: We investigate the structural and vibrational properties of glassy B2O3 using first-principles molecular dynamics simulations. In particular, we determine the boroxol rings fraction f for which there is still no consensus in the literature. Two numerical models containing either a low or a high level of boroxol rings are tested against a gamut of experimental probes (static structure factor, Raman, 11B and 17O NMR data). We show that only the boroxol-rich model (f=75%) can reproduce the full set of observables. Total-energy calculations show that at the glass density, boroxol-rich structures are favored by about 6 kcal/(mol boroxol). Finally, the liquid state is explored in the 2,000-4,000 K range and a reduction of f to 10%-20% is obtained.
authors.affiliation: IMPMC, CNRS-IPGP-Universités Paris 6 et 7, 140, rue de Lourmel, Paris, France.
authors.forename: Guillaume
authors.initials: G
authors.lastname: Ferlat
authors.forename: Thibault
authors.initials: T
authors.lastname: Charpentier
authors.forename: Ari Paavo
authors.initials: AP
authors.lastname: Seitsonen
authors.forename: Akira
authors.initials: A
authors.lastname: Takada
authors.forename: Michele
authors.initials: M
authors.lastname: Lazzeri
authors.forename: Laurent
authors.initials: L
authors.lastname: Cormier
authors.forename: Georges
authors.initials: G
authors.lastname: Calas
authors.forename: Francesco
authors.initials: F
authors.lastname: Mauri