Science Abstract
Abstract
The relative influence
of thermal and quantum fluctuations on the proton
transfer properties of the charged water complexes
H5O
2+
and
H3O
2-
was investigated using ab initio
techniques.
These small systems can be considered as prototypical representatives
of strong and intermediate strength
hydrogen bonds.
The shared proton in
the strongly hydrogen bonded
H5O
2+
was found to behave in an
essentially classical manner, whereas in the
H3O
-
low--barrier
hydrogen bond,
quantum zero--point motion
was found to play a crucial role
even at room temperature.
This behavior
can be traced back to a small difference
in the oxygen--oxygen separation,
and hence to the strength of the hydrogen bond.