Superconductivity in CaH $$_{6}$$ 6 and ThH $$_{10}$$ 10 through fully ab initio Eliashberg method and self-consistent Green’s function

Abstract

Abstract Pressurized hydrogen-based superconductors are phonon-mediated superconductors that exhibit high phonon frequencies. In these superconductors, in addition to the density of states (DOS) at the Fermi energy ( $$E_F$$ E F ), the energy dependence of the DOS around $$E_F$$ E F becomes important for evaluating their transition temperature ( $$T_c$$ T c ). Systems with peak structures in the DOS around $$E_F$$ E F , such as $$Im\bar{3}m$$ I m 3 ¯ m H $$_{3}$$ 3 S and $$Fm\bar{3}m$$ F m 3 ¯ m LaH $$_{10}$$ 10 , highlight this point. We use the fully ab initio Eliashberg method to investigate this phenomenon in $$Im\bar{3}m$$ I m 3 ¯ m CaH $$_{6}$$ 6 and $$Fm\bar{3}m$$ F m 3 ¯ m ThH $$_{10}$$ 10 with a dip structure in their DOS around $$E_F$$ E F . Our calculated $$T_c$$ T c values (225–235 K for CaH $$_{6}$$ 6 at 200 GPa and 156–158 K for ThH $$_{10}$$ 10 at 170 GPa) are quantitatively consistent with the experimental results. Remarkably, our results from the self-consistent treatment of the electron Green’s function contrasts with those cases with a peak structure in the DOS. This finding unifies the understanding of how DOS structures influence the evaluation of $$T_c$$ T c .