Time: 16:00 hrs

Location Room F, Delft

CNRS & Universite' Paris VI, Paris, France and Theoretical Chemistry, Vrije Universiteit, Amsterdam

In density-functional theory (DFT), which is perhaps the most widely used technique to study quantum many-electron systems, ground-state properties are calculated by minimizing an energy functional with respect to the particle density. In the Kohn-Sham approach, first formulated in 1965, this is done under the assumption that kinetic energy dominates, thus introducing a non-interacting reference system.

The approach works well in many scenarios, but as expected, runs into difficulty where particle-particle interactions play a more prominent role.

After a brief introduction to DFT, I will discuss the use of reference systems different from the non-interacting one of Kohn and Sham, giving two practical examples. The first one, more focused on applications for Chemistry, uses a system with a weak long-range interaction as a reference, able to capture near-degeneracy effects and van der Waals energies. The second one, more interesting for Physical applications such as low-density quantum dots, uses a strong- interacting system as a reference, and will be illustrated more in detail.