First-principles study of electronic properties of FeSe_1-xS_x alloys

We have studied the electronic and superconducting properties of FeSe_1-xS_x (x = 0.0, 0.04) alloys by first-principles calculations using the Korringa-Kohn-Rostoker Atomic Sphere Approximation within the coherent potential approximation (KKR-ASA-CPA). The electronic structure calculations show the ground states of S-doped FeSe to be nonmagnetic. We present the results of our unpolarized calculations for these alloys in terms of density of states (DOS), band structures, Fermi surfaces and the superconducting transition temperature of FeSe and FeSe_0.96S_0.04 alloys. We find that the substitution of S at Se site into FeSe exhibit the subtle changes in the electronic structure with respect to the parent FeSe. We have also estimated bare Sommerfeld constant (γ_b), electron-phonon coupling constant (λ) and the superconducting transition temperature (T_c) for these alloys, which were found to be in good agreement with experiments.