First‐Principles Estimation of Low‐Pressure Superconductivity in KC2H8 Ternary Hydride

Abstract

Very recently, much research progress has been made on the pressure‐induced superconducting state in ternary hydrides. Herein, an ab initio study of the KC2H8 ternary system is presented at a pressure in the range of 0–100 GPa. Its structural, electronic, dynamical, and superconducting properties are investigated, demonstrating that, at low pressure, KC2H8 is dynamically stable in a clathrate structure with space group Fmm and exhibits superconducting behavior with critical temperatures Tc in the range of 4–94 K. The important role played by C‐ and K‐derived phonon modes at low frequencies and H‐derived phonon modes at high frequencies is highlighted. Moreover, through the analysis of the hydrogen isotope effect, the conventional phonon‐mediated pairing mechanism in this system is proved.