Berlin 2005 – wissenschaftliches Programm

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MA: Magnetismus

MA 20: Poster:Schichten(1-29),Spintrsp(30-45),Ex-Bias(46-63),Spindyn(64-75),Mikromat.(76-80),Cluster(81-94),Abbv.(95-99),Obflm(100-02),SpElek.(103-09),E-Theo(110-14),Mikromag.(115-16),Spin+PÜ(117-26),Mag.Mat.(127-51),Meth.(152-55),Mol.Mag(156-59),Kondo(160-65

MA 20.73: Poster

Montag, 7. März 2005, 14:00–18:00, Poster TU C

Ab initio Calculation of Excitation Spectra in Magnetic Materials — •Manfred Niesert, Christoph Friedrich, Arno Schindlmayr, and Stefan Blügel — Institut für Festkörperforschung, Forschungszentrum Jülich, 52425 Jülich

Although spin-wave excitations play an important role in the thermodynamics of magnetic materials, theoretical studies are still mostly based on simple lattice systems with empirical parameters, such as the Heisenberg model. Constrained density-functional theory does not suffer from this disadvantage, but the frozen-magnon approximation restricts practical calculations to the adiabatic regime. Dynamical properties like excited-state lifetimes can only be obtained from a true many-body approach. The key quantity in this respect is the dynamical spin susceptibility. As a first step towards a full ab initio treatment, we investigate time-dependent density-functional theory at the level of the Kohn-Sham response function. This approach is inherently dynamical and can be made formally exact with the inclusion of an exchange-correlation kernel. In addition, quasiparticle excitations are studied using the GW approximation for the electronic self-energy. We assess the performance of these approaches for different classes of magnetic materials. The implementations are based on the full-potential linearized augmented plane-wave (FLAPW) method.