Phase segregation dynamics for the Blume-Capel model with Kac interaction?

We consider the Glauber and Kawasaki dynamics for the Blume-Capel spin mode l with weak long-range interaction on the infinite lattice: a ferromagnetic d-dimensional lattice system with the spin variable sigma taking values in {-1, 0, 1} and pair Kac potential gamma(d)(gamma(\ i - j \)), gamma > 0, i ,j is an element of Z(d). The Kawasaki dynamics conserves the empirical ave rages of sigma and sigma(2) corresponding to local magnetization and local concentration. We study the behaviour of the system under the Kawasaki dyna mics on the spatial scale gamma(-1) and time scale gamma(-2). We prove that the empirical averages converge in the limit gamma --> 0 to the solutions of two coupled equations, which are in the form of the flux gradient for th e energy functional. In the case of the Glauber dynamics we still scale the space as gamma(-1) but look at finite time and prove in the limit of vanis hing gamma the law of large number for the empirical fields. The limiting f ields are solutions of two coupled nonlocal equations. Finally, we consider a nongradient dynamics which conserves only the magnetization and get a hy drodynamic equation for it in the diffusive limit which is again in the for m of the flux gradient for a suitable energy functional. (C) 2000 Elsevier Science B.V. All rights reserved.