Long-term stability of the dead-zone in proto-planetary disks

We present 3D global non-ideal MHD simulations with a self consistent dynamic evolution of ionization fraction of the gas as result of reduced chemical network. We include X-ray ionization from the star as well as cosmic ray ionization. Based on local gas density and temperature in our chemical network, we determine the magnetic resistivity, which is fed back in MHD simulations. Parameters for dust size and abundance are chosen to have accreting layers and a laminar ``dead'' mid-plane.