The structural, elastic and electronic properties of marcasite FeS2 under pressure

Abstract

Employing the spin-polarized first-principles calculations, we have investigated the structural, elastic and electronic properties of marcasite FeS2 (m-FeS2) under pressure from 0 to 15 GPa. At zero pressure, the m-FeS2 is a non-magnetic semiconductor with an indirect band gap of 1.17 eV. The conduction band minimum (CBM) is mainly contributed by Fe-t2g states and a little by Fe-eg states, while the valence band maximum (VBM) is completely contributed by Fe-t2g states. The m-FeS2 is mechanically stable in the range of considered pressure. The c axis is the easiest to compress, while b axis is the hardest to compress. Both the brittle nature and covalent combination are observed for m-FeS2. With increasing pressure, the bulk modulus, shear modulus, Young's modulus, Poisson's ratio, anisotropy index AU, density, longitudinal, transverse, average elastic wave velocities, Debye temperature and minimum thermal conductivity of m-FeS2 increase smoothly, and both a small red shift for VBM and a small blue shift for CBM result in an increase of band gap.