UNIVERSALITY AND SCALING FOR THE STRUCTURE FACTOR IN DYNAMIC ORDER-DISORDER TRANSITIONS

The universal form for the average scattering intensity from systems u ndergoing order-disorder transitions is found by numerical integration of the Langevin dynamics. The result is nearly identical for simulati ons involving two different forms of the local contribution to the fre e energy, supporting the idea that the model A dynamical universality class includes a wide range of local free-energy forms. An absolute co mparison with no adjustable parameters is made to the forms predicted by theories of Kawasaki-Yalabik-Gunton, Ohta-Jasnow-Kawasaki, and Maze nko. The numerical results are well described by the Ohta-Jasnow-Kawas aki theory, except in the crossover region between scattering dominate d by domain geometry and scattering determined by Pored's law. [S1063- 651X(98)04411-0].