  Substructures in PPDs, whose ubiquity was unveiled by recent ALMA
observations, are widely discussed regarding their possible origins. We carry
out global full magnetohydrodynamic (MHD) simulations in axisymmetry, coupled
with self-consistent ray-tracing radiative transfer, thermochemistry, and
non-ideal MHD diffusivities. The abundance profiles of grains are also
calculated based on the global dust evolution calculation, including sintering
effects. We found that dust size plays a crucial role in the ring formation
around the snow lines of protoplanetary disks (PPDs) through the accretion
process. Disk ionization structures and thus tensorial conductivities depend on
the size of grains.When grains are significantly larger than PAHs, the
non-ideal MHD conductivities change dramatically across each snow line of major
volatiles, leading to a sudden change of the accretion process across the snow
lines and the subsequent formation of gaseous rings/gaps there. On the other
hand,the variations of conductivities are a lot less with only PAH sized grains
in disks and then these disks retain smoother radial density profiles across
snow lines.
