Properties of a statistical model of ice at low temperatures.

A simple statistical model for ice is presented, based on a point charge model for H2O. To simulate this model, a Monte Carlo algorithm is constructed that samples proton configurations according to the Boltzmann distribution. The ground state of the model is numerically found to be an ordered nonferroelectric state with a unit cell of eight water molecules. The same structure has been previously proposed for the low-temperature phase of ice, called ice XI, on the basis of water–water potential calculations. The model is simulated at various temperatures, and the internal energy, entropy, and static dielectric constant are obtained as a function of the temperature. The model has a phase transition towards the ground state at T=36 K, and no partial ordering is observed. This transition is compared with the phase transition towards ice XI in KOH-doped ice. [ABSTRACT FROM AUTHOR]