GW Calculations Overcoming DFT Band Gap Problem

An efficient method of DFT/LDA band-gap correction

It has been shown that the underestimated by DFT/LDA(GGA) band-gap can be efficiently corrected by an averaging procedure of transition energies over a region close to the direct band-gap transition, which we call the ∆(EIG) method (the differences in the Kohn–Sham eigenvalues). For small excitations the averaging appears to be equivalent to the ∆(SCF) approach (differences in the self-consiste...

Photonic Band Gap Calculations : Inward and Outward Integral

Strong renormalization of the electronic band gap due to lattice polarization in the GW formalism.

The self-consistent GW band gaps are known to be significantly overestimated. We show that this overestimation is, to a large extent, due to the neglect of the contribution of the lattice polarization to the screening of the electron-electron interaction. To solve this problem, we derive within the GW formalism a generalized plasmon-pole model that accounts for lattice polarization. The resulti...

Accelerating GW calculations with optimal polarizability basis

We present a method for accelerating GW quasi-particle (QP) calculations. This is achieved through the introduction of optimal basis sets for representing polarizability matrices. First the real-space products of Wannier like orbitals are constructed and then optimal basis sets are obtained through singular value decomposition. Our method is validated by calculating the vertical ionization ener...

Band gap renormalization in photoexcited semiconductor quantum wire structures in the GW approximation

We investigate the dynamical self-energy corrections of the electron-hole plasma due to electron-electron and electron-phonon interactions at the band edges of a quasi-one dimensional (1D) photoexcited electron-hole plasma. The leading-order GW dynamical screening approximation is used in the calculation by treating electron-electron Coulomb interaction and electron-optical phonon Fröhlich inte...