Structural and vibrational properties of a calcium aluminosilicate glass: Classical force-fields vs. first-principles

Magali Benoit (1) , Patrick Ganster (2) , Jean-Marc Delaye (3) , Walter Kob (4)

1 CEMES - Centre d'élaboration de matériaux et d'études structurales
2 CRMCN - Centre de recherche de la matière condensée et des nanosciences
3 LCLT - Laboratoire d'Etudes du Comportement à Long Terme des matériaux de conditionnement
4 LCVN - Laboratoire des colloïdes, verres et nanomatériaux

Using classical and ab initio molecular-dynamics (MD) simulations, we have studied a calcium aluminosilicate glass of composition (SiO2)_0.67-(Al2O3)_0.12-(CaO)_0.21}. Samples with 100 and 200 atoms were generated by classical MD simulations using a potential with 3-body interactions. Although we observe, for the model with 100 atoms, finite size effects for some structural properties, these effects are substantially reduced if the glass structure is refined by the ab initio MD simulations. In addition, some structural characteristics such as the Ca-O bond length and the angular distributions are improved by the ab initio description. The structural and vibrational characteristics of these glass samples are compared to that of a glass that has been quenched from the melt using first-principles simulations. The main differences are found on the SiOSi and SiOAl angular distributions and on the apparition of high-frequency bands in the partial Ca vibrational density of states for the classically generated glass samples.

Mots clés: Physical Sciences

Magali Benoit, Patrick Ganster, Jean-Marc Delaye, Walter Kob. Structural and vibrational properties of a calcium aluminosilicate glass: Classical force-fields vs. first-principles. Molecular Simulation, 2007, 33 (13), pp.1093-1103. ⟨10.1080/08927020701541006⟩. ⟨hal-00515013⟩