From the accurate measurement of intermolecular
vibrational frequencies and cluster structures, we can determine the
corresponding IPS with great accuracy and detail. This involves solving
a high-dimensional (n &Mac179; 6) scattering problem with high accuracy
and efficiency. New computational algorithms have been developed for
this purpose, based on a highly efficient discrete variable representation
for the intermolecular Hamiltonian. An IPS for the water dimer has recently
been determined using these methods, and will seek to build on these
results.
- Determination of an Effective
Pair Potential For Liquid Water.
From the knowledge of structures and cooperativity
effects deduced from the spectra and IPS of water clusters, new effective
pair potentials are being developed for describing liquid water in molecular
dynamics simulations. Depicted
in the cartoon above is an example of a tunneling motion that occurs
in the water trimer (a cluster of three water molecules), along with
the signature spectral signal for this motion obtained by VRT (Vibrational
Rotational Tunneling) laser spectroscopy, and the potential energy barrier
through which the tunnelling occurs.
|