Questaal
From the about page
Questaal is a suite of first-principles electronic structure programs. The codes can be used to model arbitrary materials, but they are mostly designed to answer condensed-matter theory questions about solid state (periodic) structures. The majority of the codes use an all-electron implementation of density-functional theory. This includes several forms (Hamiltonian and Green’s function) that serve different purposes. The feature that distinguishes Questaal from other implementations of electronic structure, is its all-electron implementation of many-body perturbation theory, especially its implementation of a quasiparticle self-consistent form of GW, (QSGW). A tight-binding based on user-supplied empirical Hamiltonians is also supported. Other features include the ability to perform calculations in Dynamical Mean Field Theory in conjunction with QSGW (DMFT-QSGW), the Bethe Salpeter Equation (BSE), and direct (Green Function) solution of the Dirac equation.
The user familiar with VASP might recognize the similarities, focusing on periodic structures. But also the drastic differences: free, all-electron implementation, and focuses on GW methods. As of the 2024 workshop, the number of atoms that could be handled were relatively small, around 40 atoms on very large high-performance computing architecture.
PROGRAMS
computing programs