Abstract: We calculate the equilibrium geometry structure and the anharmonic force field of OCN4 by using B3LYP, B3p86, B3pw91 and MP2 methods combining? with cc-pVnZ (n=D,T) basis sets. From the calculated results, we can see that the calculated values of DFT methods are very close to each other and excellent agreement well with experimental values. Comparing with the changes caused by methods, the basis sets playing the predominant role. Overall, the DFT methods combining cc-pVTZ basis set provide more reliable results of spectroscopic constants and anharmonic force field of OCN4.
