Reaction kinetics of non-localised particle–trap complexes

Abstract

The classical transition state theory for calculating complex dissociation rates requires separation of time scales. It is shown here that this condition is satisfied for complexes with long-range interaction, such as an edge dislocation and a cluster of self-interstitial atoms in metallic materials. Hence, one can apply the equations for first-order reactions with a rescaled mean dissociation time and the cross-section of complex formation. The rescaling coefficient is the Eyring transmission coefficient. A general expression for this coefficient through the first two moments of the distribution function of dissociation times is derived. It is shown that it is equal to unity if the dividing surface between ‘bound’ and ‘free’ states is defined as that where the interaction energy is equal to the thermal energy.

Keywords:

• transition state theory
• dissociation reactions
• complexes
• edge dislocations
• metals

Acknowledgements

AVB acknowledges a research grant from the UK Engineering and Physical Sciences Research Council. Research at ORNL was sponsored by the Division on Materials Sciences and Engineering (RES and YNO) and the Office of Fusion Energy Sciences (SIG), US Department of Energy, under contract no. DE-AC05-00OR22 725 with UT-Battelle, LLC.