Studying the electronic structure of FeSi & CoSi by using DFT+DMFT

Abstract

Hubbard U plays a vital role in ab-initio calculations for strongly correlated materials. Involving an appropriate value of U for advanced techniques like density functional theory (DFT) and dynamical mean field theory (DMFT), can help us to understand various physical properties of these systems. Here, we studied the occupied states of FeSi and CoSi by using DFT+embedded DMFT method. The x-ray photoelectron spectra for both materials are compared with partial density of states (PDOS) for Fe 3d and Co 3d orbitals obtained from DFT+eDMFT. For the study, U has been calculated by using constrained DFT technique. For the calculation of effective Coulomb interaction Ueff, PDOS around the Fermi level (EF) shows negligible participation of 3d states for impurity atoms Fe & Co in FeSi and CoSi, respectively. The d-linearization energy (Ed) is kept as ∼40 eV above EF for this calculation. This plot indicates the appropriate evaluation of Ueff for FeSi and CoSi as ∼4.4 eV and 4.5 eV, respectively. With the computed values of U, DFT+eDMFT method has qualitatively explained the occupied states of both the materials.