Hohenberg-Kohn theorem for the lowest-energy resonance of unbound systems

TL;DR

This paper extends the Hohenberg-Kohn theorem to the lowest-energy resonances of unbound systems, enabling density functional theory applications to negative electron affinities.

Contribution

It introduces a rigorous extension of the Hohenberg-Kohn theorem applicable to unbound systems' resonances, broadening DFT's scope.

Findings

Extension of HKT to unbound system resonances

Application of Gel'fand Levitan theorem in this context

Framework for DFT calculations of negative electron affinities

Abstract

We show that under well-defined conditions the Hohenberg-Kohn theorem (HKT) can be extended to the lowest-energy resonance of unbound systems. Using the Gel'fand Levitan theorem, the extended version of the HKT can also be applied to systems that support a finite number of bound states. The extended version of the HKT provides an adequate framework to carry out DFT calculations of negative electron affinities.