Seminar organised by EMAT

Subject : Computer simulations used for a search for Sb-Te, Bi-Te and Bi-Se groundstate structures

Speaker: Kirsten Govaerts, EMAT, University of Antwerp

Abstract:

It is common now to consider computation as a third branch of science, besides theory and experiment. The purpose of doing modeling and simulation is to gain understanding and insight, and the benefits are that modeling and simulation can be cheaper, quicker, and easier than experimentation alone.  The aim of our work was to find the Sb-Te, Bi-Te and Bi-Se groundstate structures, with ab initio techniques, and to investigate their energetics and electronic properties. These materials have different important applications in thermoelectrics, phase change materials, and as topological insulators. Using an effective one-dimensional cluster expansion in combination with first-principles electronic structure calculations, groundstates of Sb-Te, Bi-Te and Bi-Se can be found without making the dataset of ab initio calculated structures unreasonably large. In order to get a fast convergence we used a (pseudo)ternary cluster expansion, which takes into account the formation of Sb or Bi bilayers after relaxation due to a Peierls distortion of the lattice. The first-principles electronic structure calculations are done within the Density Functional Theory (DFT)-formalism and we explicitly took into account the van der Waals forces, known to be important in these structures.

When and where: Friday, June 22, 2012 at 11.30 h in room X.009, Campus Groenenborger