  The grand question of star and planet formation is the distribution of
magnetic flux in the protoplanetary disks. To answer it, a detailed
self-consistent chemical evolution is needed to describe the magnetic
dissipation in the collapsing core accurately. We use a chemo-dynamical version
of RAMSES to follow the evolution of collapsing dense cores for a range in the
dust size assumptions. The number density of dust and it's mean size are
affecting the efficiency of the charge capturing and thus the chemistry. The
chemical abundances for the range of dust sizes are produced by RAMSES and
serve as an input to calculations of Ohmic, ambipolar and Hall diffusivity
terms. We find that Ohmic resistivity only plays a role at the late stage of
the collapse where gas density exceeds few times $10^{13}\rm cm^{-3}$.
Ambipolar diffusion is a dominant magnetic diffusivity term in cases where mean
dust size is a typical ISM value or larger. We show that the assumption of a
fixed 'dominant ion' mass can change the ambipolar diffusion up to one order of
magnitude. 'Negative' Hall effect is dominant during the collapse in case of
mean dust size of 0.02 $\mu$m and smaller, the effect which we connect to the
dominance of negatively charged grains. We find that the Hall effect's sign
reversal is depending on relative contribution of negatively charged dust to
the hall conductivity. The dust grain mean size appears to be the parameter
dividing the collapsing clouds in Hall-dominated and ambipolar-dominated
clouds, and thus affecting the size of the new-born disks. We propose to link
the dust properties and the occurance and size of disk structures in Class 0
YSO's. The proper accounting for dust grain growth in the radiative
magneto-hydrodynamical collapse models appear to be be as important as coupling
the dynamics of the collapse with the chemistry.
