The structure of the AlOH molecule is investigated by the ab initio SC
F and MP3 methods. The 6-311G and well-tempered Gaussian-type basis se
ts are supplemented by triple polarization functions. The most stable
geometry is a bent form, with an AlOH angle of 163-degrees. The potent
ial energy curve for H rearrangement from HAlO to AlOH is calculated a
long with the vibrational frequencies and intensities. The stabilizati
on energy due to bending of the AlOH angle is small in comparison with
the zero-point vibrational energy of the bending mode. The experiment
al average structure of AlOH is expected to be linear.