Modelling the plateaus in the Kohn-Sham and Pauli potentials

Density functional theory (DFT) is the leading theoretical framework used to describe electronic structure of materials. The most common approach in DFT is that of Kohn and Sham describes a material – a system of N interacting electrons – via a fictitious system of N non-inteacting electrons subject to an effective potential termed the Kohn-Sham (KS) potential. The Kohn-Sham (KS) potential – a central quantity DFT – is known to build up plateaus and exhibit sharp spatial steps when describing the processes of dissociation, ionization, excitation and charge transfer. In this talk we show that the Pauli potential – a central quantity in orbital-free DFT (OF-DFT) and in the exact electron factorization (EEF) method – exhibits plateaus and steps, as well. We find the height of the plateau that builds up as a result of electron addition, we examine which terms of the Pauli potential contribute to the plateau (and which aren’t) and finally we model the spatial form of the plateau function. We back up our analytical findings by numerical examples. Our detailed analysis of the Pauli potential sheds light also on the step structure of the KS potential, which we discuss in our talk.