Results of Model Ice_small, where all ice is on the surface of a = 0.037 µm grains (top) and Model Ice_large with ice on the 0.232 µm grains (bottom). Left: ice thickness (black lines) changes with T_d (red). The thicker lines show larger grains. Right: ice (solid lines) and gas-phase (dotted lines) abundances of the major ice species relative to H₂. This is to be compared with Model Standard in Fig. 2.