Invariance principle for symmetric diffusions in a degenerate and unbounded stationary and ergodic random medium

We study a symmetric diffusion X on R-d in divergence form in a stationary and ergodic environment, with measurable unbounded and degenerate coefficients a(omega). The diffusion is formally associated with L(omega)u = del . (a(omega)del u), and we make sense of it through Dirichlet forms theory. We prove for X a quenched invariance principle, under some moment conditions on the environment; the key tool is the sublinearity of the corrector obtained by Moser's iteration scheme.