Long time scale evolution of radiation-induced defects in Er2O3

The diffusion of point defects after an irradiation event in Er2O3 is considered. It is shown that saddle point finding methods find one transition that is a rank-2 saddle and a method is proposed to determine the attempt frequency for the transition in this case. Different methods were used to study the point defect transitions which showed good agreement at the lower temperatures but which diverged at high temperature due to anharmonic effects. The diffusion coefficients for the point defects were calculated which indicated that the calculated values could differ by up to a factor of 3 if the exponential prefactor in the Arrhenius expression was not accurately determined. Point defect diffusion in a perfect crystal was shown to be independent of direction.