Quasiparticle Self-Consistent GW Method Based on the Augmented Plane-Wave and Muffin-Tin Orbital Method

We have developed the quasiparticle self-consistent GW (QSGW) method based on a recently developed mixed basis all-electron full-potential method (PMT method), which uses the augmented plane waves (APWs) and the highly localized muffin-tin orbitals (MTOs) simultaneously. We call this PMT-QSGW. Because of the two types of augmented bases, we have an efficient description of one-particle eigenfunctions in materials with a small number of basis functions. In QSGW, we have to treat a static nonlocal exchange-correlation potential, which is generated from the self-energy. We expand the potential in the highly localized MTOs. This allows us to carry out stable interpolation of the self-energy in the whole Brillouin zone. In addition, we have improved the offset-Gamma method for the Brillouin zone integration, so that we take into account the anisotropy of the screened Coulomb interaction in the calculation of the self-energy. For GaAs and cubic SiO2, we checked the convergence of calculated band gaps on cutoff parameters. PMT-QSGW is implemented in a first-principles electronic structure package ecalj, which is freely available from github.