title: The Total Position Spread in mixed-valence compounds: A study on the H4+ model system.
abstract: The behavior of the Total Position Spread (TPS) tensor, which is the second moment cumulant of the total position operator, is investigated in the case of a mixed-valence model system. The system consists of two H2 molecules placed at a distance D. If D is larger than about 4 bohr, the singly ionized system shows a mixed-valence character. It is shown that the magnitude of the TPS has a strong peak in the region of the avoided crossing. We believe that the TPS can be a powerful tool to characterize the behavior of the electrons in realistic mixed-valence compounds.
authors.affiliation: P. A. M. Università di Bologna, Dipartimento di Chimica Industriale "Toso Montanari,", Viale Risorgimento 4, I-40136, Bologna, Italy.
authors.forename: Gian Luigi
authors.initials: GL
authors.lastname: Bendazzoli
authors.affiliation: Laboratoire de Chimie et Physique Quantiques, Université de Toulouse et CNRS, 118, Route de Narbonne, F-31062, Toulouse Cedex, France.
authors.forename: Muammar
authors.initials: M
authors.lastname: El Khatib
authors.affiliation: Laboratoire de Chimie et Physique Quantiques, Université de Toulouse et CNRS, 118, Route de Narbonne, F-31062, Toulouse Cedex, France.
authors.forename: Stefano
authors.initials: S
authors.lastname: Evangelisti
authors.affiliation: Laboratoire de Chimie et Physique Quantiques, Université de Toulouse et CNRS, 118, Route de Narbonne, F-31062, Toulouse Cedex, France.
authors.forename: Thierry
authors.initials: T
authors.lastname: Leininger
keywords: H4+; Localization Tensor; Total Position Spread tensor; full CI; mixed‐valence systems