Abundances of various species X, n(X)/ n _H, as functions of the mean density of the cloud core, n _H, by number of hydrogen nucleus. In the case where ionization by long- and short-lived radionuclides are taken into account with , the abundances are shown by the solid lines, and the total ionization rate is shown by the dot-dashed line in the upper part of the panel. In the case of where ionization by short-lived radionuclides is neglected, the abundances are shown by the dashed lines, and the total ionization rate by the dotted line. Grains with electric charge ℓ e are denoted as G(ℓ). We have taken the ionization rate of a hydrogen molecule by cosmic rays outside the core, . We have assumed that only 20% of the volatile elements C and O and 2% of the refractory elements such as metals are in the gas phase and the rest are in dust grains, and all dust grains have a radius 1 × 10 ⁻⁵ cm.