Using generalized gradient approximation method to study the electronic structure of ferromagnetic nitride Fe16N2

The electronic structure of Fe₁₆N₂ is calculated by using the linear muffin-tin orbital method in the atomic-sphere approximation (LMTO-ASA). The recently proposed generalized gradient approximation (GGA) is used in this density functional calculation. In the GGA method, through considering the gradients of the density, the exchange-correlation effect is taken into account more sufficiently than in the standard local-spin-density approximation (LSDA). The total energy calculated with GGA is lower than that with LSDA. Magnetic moments at three different sites of Fe atom (FeI, FeII and FeIII) are 2.20, 2.55, and 2.70 μB respectively. Large enhancements of magnetic moment are observed in FeII and FeIII, which are located farther from N than FeI. There is no significant difference in calculated magnetic moments and density of state between the two approaches (GGA and LSDA)