The accurate calculation of nitrogen hyperfine coupling constants ($A_{\text{N}}$ value) for different N-centred radicals is still a challenge. Since the different rehybridization of hybrid orbitals could be regarded as the main discrepancy between nitrogen centered radicals with the presence (LP) and absence (NLP) of lone pair of electrons, the spin polarization contribution to$A_{\text{N}}$ value arising from valence orbitals (SOP effect) are more important than spin polarization effect (SP) for NLP radicals. Considering this effect, 159 nitrogen centered radicals have been calculated using the B3LYP density functional with different Pople basis sets. Compared with current methods using same basis set, for 52 nitrogen radicals with lone electron pair(such as Aniline•, C₄H₈N•, etc.) and dominant SP effect, comparable results to literature was got by B3LYP level with 6-31++G(3d,3p) basis set, however, for 122 nitrogen radicals without lone electron pair(such as DMPO/•OH, C₄H₈NH⁺•, etc.), better computational accuracy (RMS=0.118) was achieved by B3LYP level with 6-31++G basis set and IEFPCM solvent model which can reflect the significant SOP effect in this kind of radicals.

氮超细偶合常数的精确计算（${\mathrm{一个}}_{\text{ñ}}$值）以不同的N中心自由基仍然是一个挑战。由于杂化轨道的不同再杂化可以被认为是存在两个孤对电子的以氮为中心的自由基之间的主要差异，因此自旋极化对${\mathrm{一个}}_{\text{ñ}}$对于NLP自由基，价轨道（SOP效应）引起的数值比自旋极化效应（SP）更重要。考虑到这种影响，使用B3LYP密度泛函和不同的Pople基集计算了159个以氮为中心的自由基。与目前使用相同基集的方法相比，对于具有独立电子对的52个氮自由基（如苯胺•，C ₄ H ₈ N•等）和显性SP效应，B3LYP水平为6-时可获得与文献相当的结果。但是，对于没有孤立电子对的122个氮自由基（例如DMPO /•OH，C ₄ H ₈ NH ⁺），其基序为31 ++ G（3d，3p）•等），通过具有6-31 ++ G基集的B3LYP水平和IEFPCM溶剂模型获得了更好的计算精度（RMS = 0.118），这可以反映这种自由基中显着的SOP效果。