Abstract: In this paper, we study the electronic band structure and the ferromagnetic properties of the organic radical p-NPNN by employing density-functional theory with generalized gradient approximation (GGA) and local-spin density approximation (LSDA). The density of states, the total energy, and the spin magnetic moment are calculated. The calculations reveal that the δ-phase of p-NPNN has a stable ferromagnetic ground state. It is found that an unpaired electron in this compound is localized in a single occupied molecular orbital (SOMO) constituted primarily of π^*(NO) orbitals, and the main contribution of the spin magnetic moment comes from the π^*(NO) orbitals. By comparison, we find that the GGA is more suitable to describe free radical systems than LSDA.

Key words: electronic structure, ferromagnetic properties, denstiy-functional theory