  The vertical structure of the accretion disks of young stars with fossil
large-scale magnetic field is studied. The equations of magnetostatic
equilibrium of the disk are solved taking into account the stellar gravity, gas
and magnetic pressure, turbulent heating, and heating by stellar radiation. The
modelled physical structure of the disk is used to simulate its chemical
structure, in particular, to study the spatial distribution of CN molecules.
The disk of the typical T Tauri star is considered. Simulations show that the
temperature within the disk in the region $r<50$ au decreases with height and
density profiles are steeper than in the isothermal case. Outside the `dead'
zone, vertical profiles of the azimuthal component of the magnetic field are
nonmonotonic, and the magnetic field strength maximum is reached within the
disk. The magnetic pressure gradient can cause an increase in the disk
thickness in comparison with the hydrostatic one. The CN molecule concentration
is maximum near the photosphere and in the disk atmosphere where the magnetic
field strength at chosen parameters is $\sim 0.01$ G. Measurements of the
Zeeman splitting of CN lines in the submm range can be used to determine the
magnetic field strength in these regions of accretion disks.

Solar and Stellar Astrophysics