Fully optimized calculation and vibrational analysis for nitrogen and pseudo-benzene N₆ were carried out using density-functional theory (DFT) at B3LYP/6-311++G(d, p) level. The thermodynamic properties at different temperatures were obtained from vibrational analysis, and the relationship between temperature and thermodynamic properties was deduced. Molecular mechanics (MM) method with Compass and Dreiding force fields were used to predict molecular packing for N₆ among the 7 most probable space groups (P2₁/c, P-1, P2₁2₁2₁, P2₁, Pbca, C2/c, and Pna2₁), respectively. Standard free energy changes of reaction 3N₂(g)→N₆(s) were calculated. The synthetic feasibility was analyzed with thermodynamics and reaction mechanism was predicted. Results show that N₆ belongs to C2/c space group, the reaction 3N₂(g)→N₆(s) is feasible when temperature is below 61.6 K and the π bond delocalization has a decisive role in the reaction.