CASUS Institute Seminar, Dr. Maria Hellgren, L’Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie (IMPMC), Sorbonne University, Paris (France)
In this talk Maria will introduce an approach for generating accurate correlation energy functionals in density functional theory (DFT). Starting from an exact expression based on the adiabatic connection fluctuation-dissipation theorem, successively better functionals are constructed via the linear response kernel of time-dependent DFT, some of which can be directly related to approximations within many-body perturbation theory. Already the lowest level of approximation, known as the random phase approximation (RPA), has been shown to solve long-standing problems for DFT, such as static correlation and van der Waals forces. Here, Maria will focus on a functional that goes beyond RPA by including the exact-exchange kernel. Using a novel plane-wave implementation, she will demonstrate the accuracy and efficiency of the RPAx via a number of applications ranging from molecules at dissociation to ice polymorphism and high-pressure solid hydrogen.