The ground state potential energy hypersurface of the GeOH+-HGeO+ syst
em has been investigated employing ab initio electronic structure theo
ry. First, geometries of two equilibrium and isomerization (1,2 hydrog
en shift) reaction transition state were determined at the self-consis
tent-held (SCF), configuration interaction with single and double exci
tations (CISD), coupled cluster with single and double excitations (CC
SD), and CCSD with perturbative triple excitations [CCSD(T)] levels of
theory using four basis sets. A qualitatively incorrect geometry is p
redicted for GeOH+ unless f functions are included in the basis set. S
econd, physical properties including dipole moments, harmonic vibratio
nal frequencies, and infrared (IR) intensities of three stationary poi
nts were evaluated at the optimized geometries. The effects of electro
n correlation reduce the dipole moment of HGeO+ by 1.25 Debye. At the
highest level of theory employed in this study, CCSD(T) using the trip
le zeta plus double polarization with diffuse and higher angular momen
tum functions [TZ2P(f,d)+diff] basis set, linear GeOH+ is predicted to
be more stable than linear HGeO+ by 71.7 kcal/mol. After correction f
or zero-point vibrational energies (ZPVEs), this energy difference bec
omes 70.3 kcal/mol. With the same method the classical barrier height
for the exothermic isomerization (1,2 hydrogen shift) reaction HGeO+--
>GeOH+ is determined to be 30.3 kcal/mol and the activation energy (wi
th the ZPVE correction) is 28.0 kcal/mol. The predicted dipole moments
of GeOH+ and HGeO+ are 0.61 and 4.64 Debye, respectively. Thus, the H
GeO+ ion may be suitable for a microwave spectroscopic investigation.
On the other hand, the GeOH+ ion may be suitable for an LR spectroscop
ic study due to the strong IR intensities of the three vibrational mod
es. The geometrical and energetic features are compared with those of
the valence isoelectronic HCO+-COH+ and SiOH+-HSiO+ systems. (C) 1995
American Institute of Physics.