Berlin 2005 – wissenschaftliches Programm

Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe

DY: Dynamik und Statistische Physik

DY 35: Glasses I (joint session DF/DY)

DY 35.3: Vortrag

Montag, 7. März 2005, 10:45–11:00, TU A060

Atomic structure and dynamics of alumina melt: A computer simulation study — •Sandro Jahn¹ and Paul A. Madden² — ¹GeoForschungsZentrum Potsdam, Sektion 4.1, Telegrafenberg, 14473 Potsdam — ²PTCL, University of Oxford, South Parks Road, Oxford OX1 3QZ, UK

The construction of accurate and transferable interatomic potentials for oxides and silicates is still a challenging task. The problem is related to the complex electronic structure that is profoundly affected by the interactions of neighboring ions. Effective interactions represented by pair potentials subsume many-body effects in some average sense and may work for a restricted set of coordination environments. However, they do not transfer well to other phases with different coordination environment or mixtures. Here we use an advanced ionic potential that allows for ion polarization, compression and aspherical deformation, and that was optimized by fitting to properties obtained from first principles calculations to study the atomic structure and dynamics of alumina melt. We show that the model is able to reproduce a number of experimental results, such as the static structure factor S(Q), the dynamic structure factor S(Q,ω) and the transport properties. Different cation coordination numbers lead to the splitting of the first peak of the Al-Al radial distribution function which might indicate the dynamic existence of high and low density regions in the melt. Extensions of the current model to multicomponent oxides and silicates will be discussed.