Question

Green function method to calculate band structure in condense matter

Answer 1

The calculation of the ground state and excited state properties of materials is one of the main goals of condensed matter physics. While the most successful first-principles method, the density-functional theory (DFT), provides, in principle, the exact ground-state properties, the many body method is the most suitable approach for studying excited-state properties of extended systems. Therefore, Green's function and various approximations for the self-energy to solve the Dyson equation. Further we present some tools for solving the Dyson equation with several approximations for the self-energy: a highly precise combined basis method providing the band structure in the Kohn-Sham approximation, and some implementations for the random-phase approximation.