The electrostatic interaction energy of water molecules in polymorphs of ice

Abstract

The Coulombic interaction energy of water molecules in hexagonal and cubic ice and in ice III, IV, V and VI has been calculated. The calculations take into account nearest neighbours up to the third shell and the probability of each orientation of these neighbours in a dendritic manner. The energy is found to increase when mutual polarization of molecules is taken into account. It is highest for molecules in cubic ice and lowest in ice VI. For a polymorph of ice the energy depends significantly upon interactions of a molecule with its second and third neighbours, with the result that breaking of some H-bonds in the ices leads to the weakening of others. The interactions with the second and third neighbours increases the energy of an isolated pair by 20 % to 35 %. Implications of these results for the use of pair-additive potentials in computer simulations of water and ice and for our understanding of the mechanical deformation of ice are pointed out.