Main formation and destruction pathways of HNC as predicted by the chemical model for the two extreme binding energy (BE) values. In the lower figure (BE = 5280 K), the dashed arrow represents an alternative pathway for the formation of HNC through H-abstraction from H₂CN. This pathway becomes prominent when the gas-phase abundance of NH₃ is low, thereby inhibiting the formation via the reaction between NH₃ and HCNH⁺.