The reaction mechanism of CS molecule with NO molecule was investigated by using ab initio and DFT. The doublet and quartet potential energy surface of the reaction of CS with NO were calculated at the B3LYP/6-311G** and CCSD(T)/6-311G** level. The results of the calculation show that the major reaction mode is C-atom of CS molecule connecting N-atom of NO in the doublet potential energy surface. The reactants initially form the linear intermediate 1 (CSNO) via the transition state TS1, and then intermediate 1 takes a series of complex isomerization to the main product P₁ (CO＋SN). The reaction process releases large heat which is －183.75 kJ/mol. The quartet state is unimportant because the potential barrier of reaction entrance is too high.

Key words: DFT, CS and NO molecule, potential energy surface, reaction mechanism