title: Dramatic changes in electronic structure revealed by fractionally charged nuclei.
abstract: Discontinuous changes in the electronic structure upon infinitesimal changes to the Hamiltonian are demonstrated. These are revealed in one and two electron molecular systems by full configuration interaction (FCI) calculations when the realm of the nuclear charge is extended to be fractional. FCI electron densities in these systems show dramatic changes in real space and illustrate the transfer, hopping, and removal of electrons. This is due to the particle nature of electrons seen in stretched systems and is a manifestation of an energy derivative discontinuity at constant number of electrons. Dramatic errors of density functional theory densities are seen in real space as this physics is missing from currently used approximations. The movements of electrons in these simple systems encapsulate those in real physical processes, from chemical reactions to electron transport and pose a great challenge for the development of new electronic structure methods.
authors: Department of Chemistry, Lensfield Rd., University of Cambridge, Cambridge CB2 1EW, United Kingdom.
authors: Aron J
authors: AJ
authors: Cohen
authors: Departamento de Química, Universidad Autónoma de Madrid, 28049 Madrid, Spain.
authors: Paula
authors: P
authors: Mori-Sánchez