  The thermal stability of accretion disk and the possibility to see a
limit-cycle behaviour strongly depends on the ability of the disk plasma to
cool down. Various processes connected with radiation-matter interaction
appearing in hot accretion disk plasma contribute to opacity. For the case of
geometrically thin and optically thick accretion disk, we can estimate the
influence of several different components of function \kappa, given by the
Roseland mean. In the case of high temperatures, the electron Thomson
scattering is dominant. At lower temperatures atomic processes become
important. The slope d log \kappa/d log T can have locally stabilizing or
destabilizing effect on the disk. Although the local MHD simulation postulate
the stabilizing influence of the atomic processes, only the global
time-dependent model can reveal the global disk stability range estimation.
This is due to global diffusive nature of that processes. In this paper, using
previously tested GLADIS code with modified prescription of the viscous
dissipation, we examine the stabilizing effect of the Iron Opacity Bump.
