Doublet instability and the molecular structure of AlO2

The possible Cs, C2v, and C∞v structures of AlO2 corresponding to the two lowest electronic states which dissociate into the neutral Al(2P) and O2(3Σg−) fragments have been investigated at the ab initio self‐consistent field (SCF) and CI levels using nonempirical pseudopotentials. The most stable structure corresponds to a C2v symmetry in the 2A2 electronic state. However, this structure presents the three‐center three‐electron Hartree‐Fock instability and CASSCF calculations were necessary to unequivocally characterize it as true minimum. Moreover, only another stable structure, of C2v geometry, was found to be a minimum, corresponding to a low‐lying excited state of 2A1 symmetry. The optimized C∞v structures were not minima on the corresponding potential energy surfaces and no evidence of any stable Cs structure was found. Calculating values are compared with the different experimental data obtained from the reaction of Al and O2 in frozen gas inert matrices.

[1]  Stefano Evangelisti,et al.  Convergence of an improved CIPSI algorithm , 1983 .

[2]  R. K. Nesbet,et al.  Self‐Consistent Orbitals for Radicals , 1954 .

[3]  F. Illas,et al.  On the inversion barriers of group 15 tricoordinate hydrides and halides: An ab initio study using analytical gradients☆ , 1988 .

[4]  A. D. McLean,et al.  Symmetry breaking in molecular calculations and the reliable prediction of equilibrium geometries. The formyloxyl radical as an example , 1985 .

[5]  I. J. Doonan,et al.  Aspects of quantum chemistry , 1977 .

[6]  F. Illas,et al.  The molecular structure of bicyclo[1.1.0]tetraarsane from ab initio calculations using analytical gradients , 1987 .

[7]  E. Davidson,et al.  Symmetry breaking in polyatomic molecules: real and artifactual , 1983 .

[8]  M. Pélissier,et al.  One‐center expansion for pseudopotential matrix elements , 1988 .

[9]  W. Hehre,et al.  Symmetry dilemma in all-electron MO theory of the allyl radical , 1973 .

[10]  G. Berthier,et al.  On symmetry dilemmas in ab initio SCF studies of allyl radical and ethylene , 1976 .

[11]  H. C. Longuet-Higgins,et al.  The Electronic Spectra of Aromatic Molecules IV: Excited States of Odd Alternant Hydrocarbon Radicals and Ions , 1955 .

[12]  P. Durand,et al.  A theoretical method to determine atomic pseudopotentials for electronic structure calculations of molecules and solids , 1975 .

[13]  F. Illas,et al.  Convergence of a multireference second-order mbpt method (CIPSI) using a zero-order wavefunction derived from an MS SCF calculation , 1986 .

[14]  R. Carbó,et al.  Elementary Unitary MO Transformations and SCF Theory , 1982 .

[15]  K. D. Carlson,et al.  Matrix reactions of molecular oxygen and ozone with aluminum atoms , 1983 .

[16]  F. Illas,et al.  Inexpensive determinations of valence virtual MOs for CI calculations , 1986 .

[17]  O. Kikuchi.  Restricted SCF and MC SCF study of the C2v and Cs structures of the allyl radical , 1980 .

[18]  F. Illas,et al.  Theoretical evidence for two geometrical isomers of AgO/sub 2/ , 1986 .

[19]  J. P. Malrieu,et al.  Iterative perturbation calculations of ground and excited state energies from multiconfigurational zeroth‐order wavefunctions , 1973 .

[20]  F. Illas,et al.  Ab initio study of the superoxides of Group 13 metals , 1986 .

[21]  J. Paldus,et al.  Doublet stability of ab initio SCF solutions for the allyl radical , 1978 .

[22]  Renzo Cimiraglia,et al.  Recent advances in multireference second order perturbation CI: The CIPSI method revisited , 1987 .

[23]  D. Gruen,et al.  Aluminum oxide sputtering: a new approach to understanding the sputtering process for binary targets. [15- and 40 kV Ar/sup +/, 15-kV H/sup +/] , 1976 .

[24]  H. Fukutome.  Unrestricted Hartree–Fock theory and its applications to molecules and chemical reactions , 1981 .

[25]  D. White,et al.  Infrared spectra of the aluminum family suboxides. Comments , 1973 .

[26]  L. V. Serebrennikov,et al.  Infrared spectra of the products of reaction of aluminium, gallium, indium, and thallium with oxygen in an argon matrix. Estimation of the fundamentals, v3, in cyclic superoxides of group iii metals , 1982 .