608 research outputs found
First-principles study of lattice instabilities in Ba_xSr_(1-x)TiO_3
Using first-principles calculations based on a variational density functional
perturbation theory, we investigate the lattice dynamics of solid solutions of
barium and strontium titanates. Averaging the information available for the
related pure compounds yields results equivalent to those obtained within the
virtual crystal approximation, providing frequencies which are a good
approximation to those computed for a (111) ordered supercell. Using the same
averaging technique we report the evolution of the ferroelectric and
antiferrodistortive instabilities with composition.Comment: 9 pages, 2 figures, Proceedings for Fundamental Physics of
Ferroelectrics, Aspen (CO), Feb. 13-20, 200
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