A rate equation for atomic ordering in mean field theory. II. General considerations

Abstract
For pt.I see ibid., vol.3, p.2963 (1991). The authors study various examples of atomic ordering processes in which it makes sense to analyse the importance of mixed kinetics. The discussion is based on Glauber and Kawasaki types of stochastic processes in a kinetic Ising model with long range interactions, described very well by the mean field approximation. It is found that in the limiting case in which one is not far from the uniform state (i.e. spatially homogeneous) and thermal equilibrium, the rate equation can be cast into the form assumed sometimes in phenomenological rate theories of mixed kinetics. This identification allows for a critical analysis of various length scales, time scales and mixing coefficients that occur in mixed kinetic processes. Finally, the possibilities of observing mixed kinetics are indicated by way of examples borrowed from atomic ordering phenomena in certain minerals, and a few general conclusions are drawn.