An Ab Initio Study of the Mono- and Difluorides of Krypton

An ab initio study of the mono-and difluorides of krypton. Results from ab initio calculations at the CCSD͑T͒ level of theory are presented for krypton monofluoride ͑KrF͒, krypton monofluoride cation (KrF ϩ), linear, ground-state krypton difluoride (KrF 2), the triplet state of krypton difluoride, and the krypton–fluorine van der Waals complex (Kr–F 2). These are the first calculations demonstrating that KrF is a bound molecule, in agreement with experimental observation. When corrected for basis-set superposition error, the calculated potential displays quantitative agreement with the attractive wall of the experimentally measured potential curve. Results are also presented for KrF ϩ and linear KrF 2 which yield accurate values for their dissociation energies. The triplet state of KrF 2 is found to have a minimum energy below that of separated atoms, and its structure is bent, with a small F–Kr–F bond angle ͑71 deg͒. The van der Waals complex, Kr–F 2 , appears to consist of an unperturbed F 2 molecule attached to a krypton atom in the expected T-shaped structure.