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Quasiparticle SelfConsistent GW Method for the Spectral Properties of Complex Materials



Description 
The GWapproximation to the formally exact manybody perturbation
theory has been applied successfully to materials for several decades. Since the
practical calculations are extremely cumbersome, the GW selfenergy is most
commonly evaluated using a firstorder perturbative approach: This is the
socalled G0W0 scheme. However, the
G0W0 approximation depends heavily on
the meanfield theory that is employed as a basis for the perturbation theory.
Recently, a procedure to reach a kind of selfconsistency within the
GW framework has been proposed. The quasiparticle selfconsistent
GW (QS GW) approximation
retains some positive aspects of a selfconsistent approach, but circumvents the intricacies of the complete GW theory, which is inconveniently based on a
nonHermitian and dynamical selfenergy. This new scheme allows one to surmount most of the flaws of the usual G0W0 at a moderate calculation cost and at a reasonable implementation burden. In particular, the issues of small band gap semiconductors, of large band gap insulators, and of some transition metal oxides are then cured. The QSGW method broadens the range of materials for which the spectral properties can be predicted with confidence. 

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