title: Is hyper-hardness more chemically relevant than expected?
abstract: In this work, the third derivative of the energy with respect to the number of electrons, the so-called hyper-hardness, is investigated to assess whether this quantity has a chemical meaning. To achieve this goal a new working expression for hyper-hardness is developed and analyzed. It transpired from this analysis that hyper-hardness, just like hardness, can measure the reactivity or the stability of electron systems. Interestingly, positive values of hyper-hardness point to quite stable species such as noble gases and molecules. On the other hand, radicals almost always display large negative values of hyper-hardness.
authors.affiliation: CEA Grenoble -INAC/SCIB/LAN (UMR-E n°3 CEA-UJF)), CEA-Grenoble, 17, rue des Martyrs, 38054, Grenoble Cedex 9, France. christophe.morell@univ-lyon1.fr
authors.forename: Christophe
authors.initials: C
authors.lastname: Morell
authors.forename: André
authors.initials: A
authors.lastname: Grand
authors.forename: Alejandro
authors.initials: A
authors.lastname: Toro-Labbé
authors.forename: Henry
authors.initials: H
authors.lastname: Chermette
mesh_terms: D004583:Electrons; D006244:Hardness; D011789:Quantum Theory; D013816:Thermodynamics