Gradual reduction of the superconducting transition temperature of H3S by partial replacing sulfur with phosphorus

Recently, using the first-principles calculations based on the virtual crystal approximation (VCA), it has been reported that hydrogen sulfide with low phosphorus substitution possesses higher critical temperature (280 K), compared to experimentally studied H3S (203 K). Herein, using the supercell method for doping, we discuss the correctness of this result through study of superconducting properties of H3S1-xPx mixture. We proved that electron-phonon coupling constants and superconducting transition temperatures (T-c) calculated using supercell approach deviate from these one obtained earlier within the framework of the virtual crystal approximation. In particular, supercell method indicates that T-c is shifted towards lower values in comparison to experimental measurements of H3S which is the evidence for failure in increasing T-c of hydrogen sulfide through partial phosphorus substitution. Moreover, the obtained trend of critical temperature as a function of pressure, in contrast to VCA approach, is consistent with experimental results.