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 m uffin-tin orbital method in the atomic-sphere approximation (LMTO-ASA) . The recently proposed generalized gradient approximation (GGA) is us ed in this density functional calculation. In the GGA method, through considering the gradients of the density, the exchange-correlation eff ect is taken into account more sufficiently than in the standard local -spin-density approximation (LSDA). The total energy calculated with G GA is lower than that with LSDA. Magnetic moments at three different s ites of Fe atom (FeI, FelI and FeIII) are 2.20, 2.55, and 2.70 mu B re spectively. Large enhancements of magnetic moment are observed in FeII and FeIII, which are located farther from N than FeI. There is no sig nificant difference in calculated magnetic moments and density of stat e between the two approaches (GGA and LSDA).