NCTS (South)


DATE2010-10-07

TIME14:10

PLACER203, 2F, NCTS, NCKU

FIELDComputational Materials Research

SPEAKER Prof. Wei Ku(顧威) - Brookhaven National Laboratory, Upton, NY, USA / Department of Physics, Stony Brook University, USA

TITLEBand Structure Unfolding and Non-Perturbation Treatment of Disordered Systems

ABSTRACTTwo 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: [1] Phys. Rev. Lett. 104, 216401 (2010) [2] arXiv:1004.1156