Electronic structure calculations based on density functional theory (DFT) have been highly successful in describing the ground state properties of a broad range of materials, including metals and alloys. However for many classes of materials and properties, DFT is not sufficient. Among other issues, it generally does not correctly describe excitations, and fails to address the strongly correlated electron problem.

The GW approximation (G = Green’s function, W = screened Coulomb interaction), is the first term in a perturbation around a interacting one-particle LDA Hamiltonian. The quasi-particle self-consistent GW (QSGW) approximation overcomes the starting point dependency by iterating G to self-consistency, and has proven successful for the calculation of band gaps and densities of states. It also contains, in a natural way, many-body effects missing in DFT, such as van der Waals interactions, dynamical screening, and plasmons.

QUESTAAL is an electronic structure code based on the all-electron full potential linear muffin-tin orbital (LMTO) methodology. Apart from a range of DFT based codes, it contains implementations of both one-shot GW and QSGW. The QUESTAAL suite also has a new extension to DMFT, enabling the investigation of strongly correlated electron systems both at the level of LDA and QSGW.

introduction to lmf:
- self-consistent DFT calculations
- energy bands & partial DOS

introduction to GW & QSGW:
- dynamical self-energy
- interacting band structure
- energy bands & partial DOS

introduction to DMFT:
- self-consistent self-energy

spectral properties based on GW:
- dielectric functions (RPA)
- dielectric functions (BSE)
- transverse magnetic susceptibility
- phonons based on GW
- modelling photoemission

spectral properties based on DMFT
- dielectric functions
- transverse magnetic susceptibility
- pairing susceptibility