Tony Paxton

Atomistic Simulation Group, School of Maths and Physics, Queen's University, Ireland

(Work with Stefano Fabris, Tony Paxton and Mike Finnis) We address the question of whether this is an order-disorder or soft-mode type transition. To do this we have done molecular dynamics simulations using a new tight-binding model for mixed ionic-covalent systems which includes self-consistently the polarizability up to the quadrupole level [1]. We map the results to a Landau expansion of the free energy. [1] M. W. Finnis et al., Phys Rev Lett, 81, 5149 (1998)