Bottom: Relative abundances $n( X) / n_{\mathrm{H}\,}$ of some representative particles on the midplane of a disk with $q=3/2$, $f_{\Sigma }=1$, $p=\frac{1}{2}$, $T_{0}=280$ K, $M_{*}=1\,M_{\odot }$, and $f_{g}=1$ as functions of the distance r from the star. We call this the fiducial model because it is expected to well represent the primitive solar nebula in an early evolutionary stage. We adopted the depletion factors of heavy elements from the gas phase $\delta _{1}=0.2$ and $\delta _{2}=0.02$, the fraction of gas phase oxygen in the form of O$_{2}$, H$_{2}$O, or OH $f_{\mathrm{O}\,_{2}}=0.7$, and the radius of dust grains $a=0.1$ μm. G(n) represents grains with electric charge ne. Top: Ionization rate ζ on the midplane as a function of r.