Phase transitions in tridymite studied using ‘Rigid Unit Mode’ theory, Reverse Monte Carlo methods and molecular dynamics simulations

Mineralogical Magazine Mineralogical Society 64:2 (2000) 267-283

Authors:

MT Dove, AKA Pryde, DA Keen

Aspects of the structure and dynamics of the CMR material Nd0.5Pb0.5MnO3

Physica B Condensed Matter Elsevier 276 (2000) 774-775

Authors:

A Mellergård, DA Keen, M Harris, RL McGreevy

Magnetic excitations of single-crystal PrBa2Cu3O6.2

PHYSICA B 276 (2000) 799-800

Authors:

SJS Lister, AT Boothroyd, NH Andersen, AA Zhokhov, AN Christensen

Abstract:

Measurements of the low-energy magnetic excitations in single-crystal PrBa2Cu3O6.2, and in YBa2Cu3O6.2 for comparison, have been performed using inelastic neutron scattering. An excitation with weak dispersion is seen, which is compared to a spin-wave model based on the lowest lying crystal field levels of the Pr ion, and including the effect of an anisotropic coupling to the Cu magnetic moments, as well as a Pr-Pr exchange interaction. (C) 2000 Elsevier Science B.V. All rights reserved.

Amorphous silica from the Rigid Unit Mode approach

Mineralogical Magazine 64:3 (2000) 377-388

Authors:

MT Dove, KD Hammonds, MJ Harris, V Heine, DA Keen, AKA Pryde, K Trachenko, MC Warren

Abstract:

We apply the Rigid Unit Mode model, which was initially developed for crystalline silicates, to the study of the flexibility of silica glass. Using a density-of-states approach we show that silica glass has the same flexibility against infinitesimal displacements of crystalline phases. Molecular dynamics simulations also show that parts of the silica structure are able to undergo large spontaneous changes through reorientations of the SiO4 tetrahedra with no energy cost.

Modeling the magnetic structure of Dy7Fe3 metallic glass

Physical Review B American Physical Society (APS) 61:1 (2000) 487-491

Authors:

L Karlsson, A Wannberg, RL McGreevy, DA Keen