Marcasite osmium nitride with high bulk modulus: First-principles calculations

Abstract

The authors propose marcasite Os N2 as a structure of the experimentally synthesized orthorhombic Os N2 compound. From the first-principles calculations, they find that the marcasite structure is more stable than the fluorite and pyrite ones and its lattice constants are in good agreement with the experiment. The calculated elastic constants for marcasite Os N2 satisfy the stability condition. The band structure shows that marcasite Os N2 is metallic. There is a pseudogap around the Fermi level of the total density of states of marcasite Os N2, which may contribute to its stability. The appearance of the pseudogap is mainly caused by the anisotropic connectivity of Os N6 octahedra. © 2007 American Institute of Physics.