Generalized renormalization group treatment of the growth kinetics of unstable systems

We discuss the generalization of a renormalization group technique developed previously for the study of ordering in unstable systems in the context of the ferromagnetic Ising model with spin-flip dynamics. Difficulties encountered in earlier work are eliminated through the use of new recursion relations dependent on a continuous spatial rescaling factorb 1. A more careful analysis and implementation of the approximation scheme is carried out. Our improved method allows the study of the anisotropy of the time-dependent structure factor and the pre-scaling behavior of the shape function.