Abstract: Density functional theory B3LYP method is used to optimize ground-state structures of NF molecule,NF⁺ and NF^- molecule ions with 6-311+ +g(df,3pd),6-311g(3d,3p) and 6-311+ +g(3df,3pd) basis sets,respectively.Frequency and single-point energy scan for NF^X(X=-1,0,+1) are calculated.With the least-square method,spectral parameters (B_e,α_e,ω_e,ω_eχ_e) of NF molecule and NF⁺ ion ground state are fitting to Murrell-Sorbie functions.Calculated results are in good agreement with experiments.Spectral parameters (B_e,α_e,ω_e,ω_eχ_e) and force constants (f₂,f₃,f₄) of NF^- molecular ion ground state are shown.

Key words: NF^X(X=-1,0,+1)molecular ion, structure, potential energy function