The electronic and geometrical structure of aluminum fluoride anions AlF[sup [minus]][sub [ital n]], [ital n]=1--4, and electron affinity of their neutral parents

Journal Article · Wed Jun 15 00:00:00 EDT 1994 · Journal of Chemical Physics; (United States)

DOI:https://doi.org/10.1063/1.466697· OSTI ID:7307584

Gutsev, G; Les, A; Adamowicz, L ^[1]

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1. Department of Chemistry, the University of Arizona, Tucson, Arizona, 85721 (United States)

The electronic and geometrical structure of AlF[sup [minus]], AlF[sup [minus]][sub 2], AlF[sup [minus]][sub 3], and AlF[sup [minus]][sub 4] as well as their neutral parents are determined at the unrestricted Hartree--Fock (UHF) and second-order unrestricted Moller--Plesset (UMP2) levels of theory. The results of the calculations are used for estimating the adiabatic electron affinity (E.A.) of the neutrals and fragmentation energies of both the neutrals and anions. All these characteristics were also recomputed using the UMP2/6-31+G* geometry at the fourth-order UMP4 level of theory. According to the results of the single-, double, triple-, and quadruple-excitation fourth-order Moller--Plesset (MP4SDTQ) calculations, the AlF molecule in the ground state has no positive E.A., AlF[sub 2] possesses a rather high E.A. value of 1.90 eV, and AlF[sub 3] has a smaller E.A. of 0.93 eV, whereas the last member in the series AlF[sub 4] possesses an extremely high E.A. of 7.96 eV. Such a large value is related to high stability of the anion towards fragmentation opposite to the neutral AlF[sub 4] whose dissociation energy is computed to be only 4--5 kcal/mol. It has been predicted that all the anions are rather stable towards detachment of a fluorine anion, and AlF[sup [minus]][sub 4] is the most stable in the series. The AlF molecule is able to attach an additional electron at large interatomic distances and form a stable anion. This indicates an increasing tendency to form resonances when the molecule is excited into a higher vibrational state. Our calculations also show that AlF in the lowest triplet state may attach an additional electron to form a metastable anion in the quartet state. This anion is predicted to be stable towards both detachment of the extra electron and dissociation. A similar increasing tendency to formation of resonance states with an additional electron with vibrational excitation is also predicted for AlF[sub 2].

• DOE Contract Number: FG03-93ER61605
• OSTI ID: 7307584
• Journal Information: Journal of Chemical Physics; (United States), Vol. 100:12; ISSN 0021-9606
• Country of Publication: United States
• Language: English

Related Subjects

74 ATOMIC AND MOLECULAR PHYSICS
ALUMINIUM FLUORIDES
ELECTRONIC STRUCTURE
GEOMETRY
ANIONS
ADIABATIC APPROXIMATION
AFFINITY
INTERATOMIC DISTANCES
METASTABLE STATES
RESONANCE
TRIPLETS
ALUMINIUM COMPOUNDS
CHARGED PARTICLES
DISTANCE
ENERGY LEVELS
EXCITED STATES
FLUORIDES
FLUORINE COMPOUNDS
HALIDES
HALOGEN COMPOUNDS
IONS
MATHEMATICS
MULTIPLETS
664100* - Theory of Electronic Structure of Atoms & Molecules- (1992-)