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Internet Electronic Journal of Molecular Design - IEJMD, ISSN 1538-6414, CODEN IEJMAT
| ABSTRACT - Internet Electron. J. Mol. Des. August 2004, Volume 3, Number 8, 464-473 |
On the Existence of the Butterfly Isomer of Al2H2:
Ab Initio Coupled-Cluster Study
Jerzy Moc and Maria Wierzejewska
Internet Electron. J. Mol. Des. 2004, 3, 464-473
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Abstract:
The recent theoretical study of the present authors revealed that
the butterfly structure of Ga2H2 subhydride was an additional
dibridged minimum on the singlet potential energy surface.
Here, the existence of this kind of isomer is studied for the
lighter Al2H2 analog in terms of thermodynamic and kinetic
stabilities using high level ab initio calculations. Geometry
optimization of the key dibridged structures were performed
using ab initio coupled-cluster singles and doubles method
incorporating a perturbative correction for triples (CCSD(T))
with all the electrons correlated (FU) and in conjunction with
the aug-cc-pVTZ basis set. Better energetics were evaluated at
the CCSD(T)(FU) level and employing aug-cc-pVrZ (r = Q,
5Z) basis sets. The calculated thermodynamic and kinetic
stabilities and IR spectra of the five Al2H2 structural isomers
1-5, including a new type nonplanar dibridged (butterfly) species
5 not reported before, have been compared. The butterfly
isomer 5 has been found to be the lowest energy structure of
Al2H2, although lying only about 1 kcal/mol below the
"previously most preferred" planar dibridged isomer 1 at the
ZPE corrected CCSD(T)(FU)/aug-cc-pV5Z computational level.
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