The bonding and migration of an O atom on a CaO(100) surface: a theoretical study

• Published in: Surface science 1992-09, Vol.275 (3), p.473-481
• Main Author: Strömberg, Dan
• Format: Article
• Language: English
• Subjects: Ab initio; Annan naturresursteknik; bond distances; CaO surface; Chemical Engineering; Condensed Matter Physics; Condensed matter: structure, mechanical and thermal properties; Den kondenserade materiens fysik; dissociation energy; Exact sciences and technology; Kemiteknik; O atom; Other Environmental Engineering; Physics; quantum calculations; Solid surfaces and solid-solid interfaces; Surface structure and topography; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); Teoretisk kemi; Theoretical Chemistry
• ISSN: 0039-6028; 1879-2758
• DOI: 10.1016/0039-6028(92)90820-V

Ab initio quantum calculations of the dissociation energies and bond distances for the bond between an O atom situated at different sites on a CaO(100) surface have been performed, using surface clusters imbedded in an array of point charges. The point charges were evaluated by a modified Ewald technique. The calculations were carried out using the CASSCF and CCI methods. Different clusters were tested. The “peroxy” bond between the O atom and a surface O 2− site was found to be the strongest, ≈ 50 kcal/mol at the CCI level compared to a triplet oxygen atom far away from the surface (∼ 100 kcal/mol compared to a singlet oxygen atom). The bond on top of a surface Ca 2+ ion was very weak, ∼ 5 kcal/mol. The surface migration of an O atom from one O 2− site to another O 2− was investigated. The barrier for the migration was calculated to ∼ 66 kcal/mol.