Third Electronic Computational Chemistry Conference
ECCC3 .
AB INITIO STUDY OF THE HYDRONIUM RADICAL.
PART I :
INVESTIGATION OF THE UHF POTENTIAL ENERGY SURFACE.
Francis F. MUGUET
Laboratoire d'Optique Appliquée (L.O.A)
C.N.R.S URA 1406,
INSERM U 451
E.N.S.Techniques Avancées
--
Ecole Polytechnique
Centre de l'Yvette
91125 Palaiseau CEDEX
FRANCE
M. P. BASSEZ
Laboratoire de Chimie Physique
I.U.T Strasbourg-Sud, Université de Strasbourg III.
72 Route du Rhin, 67400 Illkirch-Graffenstaden
FRANCE
G. Wilse ROBINSON,
Subpicosecond and Quantum Radiation Laboratory
Department of Chemistry and Department of Physics
Texas Tech University
Lubbock, TX 79409, USA
ABSTRACT
Herzberg [1] has considered the existence of
the hydronium radical, as an example of a Rydberg radical.
However, it is only, in 1984, that the
(H3O.)
radical was detected in vacuo [2].
In neutralized ion beam spectroscopy experiments [2],
intriguing
hydrogen and oxygen isotope substitution effects were observed.
The solvated hydronium
(H3O.)
radical is also a species of major interest in the domain of liquid phase reactivity, since an electron-ion
(H3
O+...e-)aq
pair has been found in femtosecond spectroscopy experiments in highly concentrated acidic solution [3].
The hydronium radical plays also a crucial role in two protic
models of
the "hydrated electron" [4].
Past theoretical studies have been unable to explain
satisfactorily experimental data in vacuo .
To check possible basis set effects, we studied the
influence of the
quality of the basis set and we
employed 8 different basis sets. We determined
optimized geometries and transitions points, at the UHF level.
We computed the ZPE and we investigated oxygen and hydrogen
substitution effects.
With the help of MO graphics, it has been possible
to shed more light on the unimolecular dissociation
mechanism, which is predicted to occur, at the UHF level,
through a Derydbergization process, as
suggested previously by Mulliken [5].
In line with previous UHF and MCSCF studies, we find that
it is not possible to explain satisfactorily experimental data,
with the
results of ab initio computations
performed at the UHF level and within the Born-Oppenheimer
approximation.
[1] G. Herzberg
Ann Rev Phys Chem.38:27-56 (1987)
[2] Gellene and Porter J.Chem.Phys. 81(12),5770-5576 (1984) ; Raksit and Porter Int.J.Mass. Spec.Ion.Proc. 76,299-306 (1987) )
[3] Y.Gauduel, S.Pommeret, A.Antonetti J.Phys.Chem. 97(1),134-142(1993) ; Y.Gauduel, pp 191-204 in Ultrafast Reaction Dynamics and Solvent Effects AIP vol..298 Y. Gauduel,P.J. Rossky Eds. AIP Press (NY) (1994).
[4] F. F. Muguet, G.W. Robinson, p 158-170 in
Ultrafast reaction dynamics and solvent effects .
AIP Conference Proceeding 298, Yann Gauduel, Peter J. Rossky Eds, AIP Press(1994). and ref. herein.
[5] Mulliken R.S Chem. Phys. Lett 46(2),197-200 (1977)
