Berlin 2012 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 43: Correlated Electrons: Metal-Insulator Transition 2
TT 43.2: Vortrag
Donnerstag, 29. März 2012, 15:15–15:30, H 3010
Modeling the disordering of the cooperative Jahn-Teller distortion in KCuF3 — •Joaquin Gabriel Miranda1, Erik Koch1, and Eva Pavarini2 — 1German Research School for Simulations Sciences, Forschungszentrum Jülich and RWTH Aachen University, 52425 Jülich — 2Institute for Advanced Simulation and JARA, Forschungszentrum Jülich, 52425 Jülich
We study the melting of the cooperative Jahn-Teller distortion. To properly describe this order-disorder transition we have to work with large real-space cells. For this we use a combination of first-principle calculations (LDA+U) and Monte Carlo (MC) simulation. First we determine the potential energy surface for displacements of the fluorine ions. Subtracting the long-ranged Coulomb terms lead to a short-ranged parametrization of the dynamical matrix for pairs of fluorine displacements. We then use the parametrized LDA+U energies as the input for Monte Carlo simulations of extended supercells to study the spacial range of the lattice ordering as a function of temperature.