Top: abundance profiles along the vertical disk direction at the radius of 300 au for HNC and HCN in the fiducial model, as well as species relevant to their formation (HCNH⁺ and e⁻) and destruction (H and O). The drop in CO abundance in the top layer reflects where CO photodissociation becomes important. Bottom: gas temperature profile along the vertical disk direction at 300 au for the fiducial model (solid line), as comparisons to carbon and oxygen depletion models (dashed line: a factor of 10; dash-dotted line: a factor of 100; and dotted line: C/O = 1.5).