Quantum Mechanical Studies of the Energetics of Ionic Defects in Icelike Systems

Previous research in this series , used model clusters to examine the energy required to produce configurational defects in ice Ih and the subsequent relaxation of the lattice. The current studies use similar cluster models to investigate the energy requirements and lattice distortions associated with the production and migration of ionic defects. Two model clusters, each containing eight water molecules, are used to study the energy required to form and stabilize an ion pair. These initial calculations suggest that the ion pair can be stabilized if relaxation and annihilation would require a simultaneous shift of three or more protons. At least in these model clusters, barrierless paths exist for the shift of two protons, leading to the recombination of the ions. The energies required for the formation, with subsequent separation and stabilization, is of the order of 1−2 eV.