Lorda Donat, AmparoIllas i Riera, FrancescRubio Martínez, JaimeTorrance, J. B.2009-10-282009-10-2819930163-1829https://hdl.handle.net/2445/9847A linear M-O-M (M=metal, O=oxygen) cluster embedded in a Madelung field, and also including the quantum effects of the neighboring ions, is used to represent the alkaline-earth oxides. For this model an ab initio wave function is constructed as a linear combination of Slater determinants written in an atomic orbital basis set, i.e., a valence-bond wave function. Each valence-bond determinant (or group of determinants) corresponds to a resonating valence-bond structure. We have obtained ab initio valence-bond cluster-model wave functions for the electronic ground state and the excited states involved in the optical-gap transitions. Numerical results are reasonably close to the experimental values. Moreover, the model contains the ionic model as a limiting case and can be readily extended and improved.9 p.application/pdfeng(c) The American Physical Society, 1993València (Química)Propietats òptiquesPel·lícules finesOrbitals atòmicsÒxidsValence (Theoretical chemistry)Optical propertiesThin filmsAtomic orbitalsOxidesinfo:eu-repo/semantics/article69864info:eu-repo/semantics/openAccess