STRUCTURE AND DYNAMICS IN HEXAGONAL ICE - A MOLECULAR-DYNAMICS SIMULATION WITH AN ABINITIO POLARIZABLE AND FLEXIBLE POTENTIAL

We perform a molecular dynamics simulation of the hexagonal solid phase of water, using a new polarizable and flexible potential which has been derived from quantum mechanical calculations. We calculate and compare with available experimental data the molecular structure, the density of states in the translational, librational, and vibrational regions as well as the acoustic dispersion relations. The molecular structure in the condensed phase is found to be in agreement with the recent interpretation of the neutron scattering data of Kuhs and Lehmann [W. F. Kuhs and M. S. Lehmann, J. Phys. (Paris) 48, Cl, 3 (1987)]. The collective low frequency modes in the simulated ice are in good agreement with the experimental data in the c-axis direction but 20% softer in the hexagonal plane.