|PLACE||R203, 2F, NCTS, NCKU|
|FIELD||Computational Materials Research|
|SPEAKER||Prof. Wei Ku(顧威) - Brookhaven National Laboratory, Upton, NY, USA / Department of Physics, Stony Brook University, USA|
|TITLE||Band Structure Unfolding and Non-Perturbation Treatment of Disordered Systems|
|ABSTRACT||Two recent developments of first-principles computational method will be presented in this talk. First, in the presence of weak translational symmetry breaking (lattice distortion, charge density wave, spin-density wave, orbital ordering,.) one is typically forced to enlarge the unit cell to incorporate the extended period. The resulting band structure then becomes less informative and a direct comparison with the original reference system becomes difficult. A Wannier function based unfolding method will be explained that unfold the band structure back to the one of the reference system, providing a direct visualization of the effects of the symmetry breaker, and each band‘s coupling to the order parameter.
Second, applying this method to disordered systems, a beyond mean-field non-perturbation method can be formulated. For the first time, the Anderson localization can be realized in first-principles calculations. This offers great opportunities in the study of doping, substitution, and vacancies in magnetic semi-conductors and correlated transition metal oxides.
Ref:  Phys. Rev. Lett. 104, 216401 (2010)  arXiv:1004.1156