Structural studies of low temperature ice Ih using a central force potential model

Publisher Website
Google Scholar
Abstract
The revised central force potentials of Stillinger and Rahman [J. Chem. Phys. 68, 666 (1978)] are used to study the binding energy, structure, and multipole moments of a periodic ice Ih sample with a unit cell of 192 water molecules. The initial configuration for the unit cell has each oxygen in a wurtzite structure and intramolecular H–O–H angles symmetrically positioned in the tetrahedral O–O–O angles. Hydrogens are placed such that the total dipole moment for the unit cell is zero and the diagonal quadrupole moments are small (≲ 10−28 esu cm2). Subject to these restrictions, a static energy minimization on the periodic ice crystal yields an optimal O–O separation, intramolecular O–H distance, and intramolecular H–O–H angle of 2.78, 0.972 A, and 101.0°, respectively. Starting from this idealized wurtzite configuration, Metropolis Monte Carlo runs on the periodic system are made at 20 and 200 K. At 20 K, the equilibrated system has an average intermolecular potential energy per molecule of ‐15.2 kcal/mol and structure factors which have decreased to about 80% of the initial values. The dipole moment for the unit cell is ≂ 3 D. The equilibrated system at 200 K appears to be modified only by temperature dependent vibrational effects.

This publication has 16 references indexed in Scilit: