First-principles predictions based on ab initio intermolecular potentials:
clusters and molecular condensed phase

Krzysztof Szalewicz, University of Delaware

Recently developed perturbational methods allow reliable calculations of
intermolecular forces and provide a rigorus decomposition of these forces
into the electrostatic, induction, dispersion, and exchange effects. This
approach can be used to compute both the pair interactions and three-body
nonadditive interactions. Such ab inito computed potentials have been
used in dynamic calculations for small clusters and in simulations of
condensed phase. Two application will be discussed: to helium and to
water. In the former case the ab initio approach is so accurate that
theoretical results are used to scale thermophysical experiments and
create new measurement standards. For water, the ab initio potentials
were used to generate rovibrational spectra of small clusters in excellent
agreement with experiment. Simulation of liquid water revealed for the
first time the role that the three-body effects play in this system. Such
simulation can also be used to help understand the anomalous properties of
water.

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