Superconducting state in the atomic metallic hydrogen just above the pressure of the molecular dissociation

Above the pressure of ∼500GPa, the molecular metallic hydrogen gets converted into the atomic phase. The properties of the superconducting state in the metallic hydrogen just above the molecular-atomic phase transition have been examined in the paper (p=539 GPa). The numerical calculations have been conducted in the framework of the Eliashberg formalism. It has been stated that the critical temperature (TC) is equal to 360 K when the Coulomb pseudopotential takes the value of 0.1. In the considered case, TC considerably exceeds the value calculated with the help of the McMillan or Allen–Dynes formula. The remaining thermodynamic parameters significantly diverge from the canonical values predicted by the BCS theory. In particular: RΔ≡2Δ(0)/kBTC=4.95RΔ≡2Δ(0)/kBTC=4.95, RC≡ΔC(TC)/CN(TC)=2.78RC≡ΔC(TC)/CN(TC)=2.78, and RH≡TCCN(TC)/HC2(0)=0.126.

► The superconducting state in atomic metallic hydrogen at 539 GPa is examined.
► The Eliashberg formalism is used to determine the thermodynamic properties.
► The observed thermodynamic properties strongly deviate from the BCS predictions.
► The results are compared with the predictions for the molecular metallic hydrogen.