Initial surface density and C/O ratio. Top: initial surface density of pebbles (blue line) and gas (black line). Bottom: C/O number ratio in the disk in pebbles and gas. Evaporation lines are labeled and indicated as dashed purple lines. Evaporation lines for molecular species with condensation temperatures higher than 704 K are not shown for simplicity (see Table 2). The solar C/O value of  0.54 is indicated as a red horizontal dashed line. We use our standard disk parameters with α = 5 × 10⁻⁴ for this simulation, as stated in Table 3.