Atomistic simulation of cristobalite at high temperature

✍ Scribed by Bourova, Ekatarina; Parker, Steven C.; Richet, Pascal

• Book ID: 126047043
• Publisher: The American Physical Society
• Year: 2000
• Tongue: English
• Weight: 375 KB
• Volume: 62
• Category: Article
• ISSN: 1098-0121
• DOI: 10.1103/PhysRevB.62.12052

✦ Synopsis

Lattice-dynamics and molecular-dynamics simulations based on the Born model of solids have been used to investigate the structural disorder present in the ␤ phase of cristobalite. We used both shell and rigid-ion interatomic potentials and compared with available experimental data the values predicted for a large number of ␣-cristobalite properties at different temperatures. Free-energy minimization at room temperature suggests the possibility of three different but energetically similar cristobalite structures. Molecular-dynamics simulations point to dynamical disorder in ␤ cristobalite at high temperatures and show its relation to these three possible modifications. This approach also demonstrates the influence of the ␣-␤ transition on structural disorder and assigns the unit-cell contraction observed at high temperature to the decrease of the first Si-Si distance due to the large thermal motion of oxygen atoms which cause the neighboring tetrahedra to come closer to each other.