Schematic showing the calculation of the thermal structure of the disk by combining both the RADMC3D Monte Carlo simulation and the diffusion equation. The Monte Carlo simulation calculates the temperature structure due to the irradiation (T_irr) from a central star, while the diffusion equation is used to solve the temperature structure at high optical depths (τ_R> 1 where τ_R is the Rosseland mean optical depth) as indicated by the red line. This high optical depth region typically starts below the disk surface. The outflow wall, warm inner envelope (T_dust> 100 K and r< 500 AU), and photodissociation region are indicated.