Study of the electronic and the structural properties of iron monosilicide via plane wave density functional theory calculations

We studied the electronic and the structural properties of iron monosilicide in low-pressure ɛ-phase structure and in the high-pressure CsCl structure via pseudopotential plane wave density functional calculations within the local spin density approximation (LSDA) and the generalized gradient approximation (GGA). The relaxation of the internal parameters of ɛ-FeSi opens up the band gap in the LSDA while it only increases the magnitude of the band gap in the GGA The structural transition from the ɛ-phase to the CsCl-phase is estimated to occur at about 19 GPa in GGA, in good agreement with the synthesis of the CsCl-phase of FeSi at 24 GPa.