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MA: Fachverband Magnetismus

MA 17: Magnetic Particles and Clusters (jointly with CPP, BP)

MA 17.5: Vortrag

Dienstag, 12. März 2013, 11:00–11:15, H22

Stability and Meta-stability of Clusters in a Reactive Atmosphere: Theoretical Evidence for Unexpected Stoichiometries of Mg_MO_x — •Saswata Bhattacharya, Sergey V. Levchenko, Luca M. Ghiringhelli, and Matthias Scheffler — Fritz-Haber-Institut der Max-Planck-Gesellschaft, Berlin-Dahlem 14195, Germany

Applying genetic algorithm and replica exchange molecular dynamics in a cascade approach we calculate structure and composition of Mg_MO_x clusters at realistic temperatures and oxygen pressures. The cascade starts with force field and goes up to density functional theory with exact exchange plus correlation in the random phase approximation.[1] The stable compositions are identified using ab initio atomistic thermodynamics. We find that at realistic environmental conditions small clusters (M = 1-5) are in thermodynamic equilibrium when x > M. Non-stoichiometric clusters are found to have in general higher spin multiplicity than stoichiometric ones. This suggests a possibility of tuning magnetic properties by changing environmental conditions.

We appreciate support from the cluster of excellence UniCat financed by the German Science Foundation (DFG).

[1] X. Ren, P. Rinke, C. Joas, and M. Scheffler, Invited Review: Random-phase approximation and its applications in computational chemistry and materials science. J. Mater. Sci. 47, 21 (2012).