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A CI pseudopotential‐based description of the low‐lying states of A g O 2
Author(s) -
Bravo G.,
FloresRiveros A.,
Novaro O.
Publication year - 1990
Publication title -
international journal of quantum chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.484
H-Index - 105
eISSN - 1097-461X
pISSN - 0020-7608
DOI - 10.1002/qua.560370607
Subject(s) - pseudopotential , excited state , chemistry , ground state , potential energy , atomic physics , ionic bonding , dissociation (chemistry) , maxima and minima , oxygen , ion , molecular physics , physics , mathematical analysis , mathematics , organic chemistry
Extensive SCF ‐ LCAO ‐ MO variational and perturbative configuration interaction ( CI ) calculations framed within an effective core potential approximation have been performed to determine the two experimentally observed geometrical isomers of A g O 2 and the interconversion route between them. These structural forms, associated to the ground‐state local minima, yield virtually the same energy, and their spontaneous interconversion is strongly indicated, which agrees fairly well with the experimental measurements. The reaction A g + O 2 → A g O 2 was theoretically analyzed along a CI fully optimized energy pathway for the ground and various excited states, within C 2 v and C s symmetry. Although a tight‐ion pair (A g +O 2 − ) character is predicted for the ground state at the equilibrium geometries, its dissociation leads to neutral rather than to ionic fragments. The study of the reaction path within C s symmetry shows an avoided crossing between the ground state and another 2 A″ potential curve where the former correlates adiabatically with the reactants A g ( 2 S) + O 2 ( 1 Δ g ). This indicates that the formation of the complex proceeds via a reactive state of molecular oxygen. The higher 2 A″ electronic curves correlate with the metal 2 P excited state, and the oxygen binding is found to be less favorable. The present results are shown to have an important bearing on the experimentally known catalytic properties of oxygen adsorbed on silver surfaces.