The midplane temperature of two-population models with ring configurations. From top to bottom, the dust surface density for the small grains at the Gaussian peak are 0.002, 0.02, and 0.2 g cm⁻² (the peak density of big grains are 31.6 times higher). From left to right, the Gaussian widths are 20, 10, and 5 au. Blue, orange and green curves represent α = 10⁻⁴, 10⁻³, and 10⁻², respectively. The gray dashed lines are the surface densities of small grains and colored dashed lines are those of big grains. The floor density over the peak density is 10⁻³. The total dust masses are shown in the top-right corner. In each panel, the dust mass depends on α. The total masses are comparable to what are shown in each panel of Figure 5.