IMPORTANCE OF ELECTROSTATIC INTERACTIONS BETWEEN NONBONDED MOLECULES IN ICE

Ab initio calculations on water dimer, trimer, Pm11 polymer, I41md prototype structure, and ice VIII shows that the dependence of the O-H bond length upon the intermolecular distance mostly depends upon environmental effects due to non-H-bonded molecules. The hydrogen bonds are found to be weaker in ice VIII and Pm11 polymer than in the I4(1)md structure. This result is consistent with recent experiments on He-H2O and H-2-H2O clathrates and emphasizes the role of interactions between nonbonded molecules. These effects can be qualitatively understood by a simple dipole-dipole electrostatic model.