Investigating the electronic structure of MSi (MÂ = Cr, Mn, Fe & Co) and calculating Ueff & J by using cDFT

We have investigated electronic band structures and partial density of states (PDOS) of inter-metallic compounds viz. CrSi, MnSi, FeSi and CoSi using density functional theory (DFT). CrSi and MnSi have metallic, FeSi has indirect semiconducting bandgap (Eg∼90 meV) and CoSi has semi-metallic ground states. On studying the similar bands around the Fermi level (Ef) of CrSi to CoSi band structures, the occupied bands are getting narrower while unoccupied ones are getting wider. Similarly, band edge in PDOS is shifting away from Ef due to increased hybridizations in the energy range ∼ -14.0 to ∼ -12.0 eV. The effective mass of holes for FeSi is found to be larger than that of electrons, giving rise to positive Seebeck coefficient and negative Hall coefficient, consistent with experimental results. For different ionic states of 3d-metal, the values of Ueff and J are evaluated using constrained DFT method. Ueff (J) for 2+ ionic state across the series are ∼3.3 (∼0.65), ∼3.7 (∼0.72), ∼4.4 (∼0.82) and ∼4.5 (∼ 0.87) in eV. λ and J are also calculated by considering Yukawa form of Coulomb interaction. λ values for 2+ ionic state along the series are ∼1.97, ∼2.07, 2.07 and 2.34 in a. u−1. 4s electrons are found to be contributing more in screening the 3d electrons as compared to 4p electrons of 3d metals.