Calculated Nb superconducting transition temperature under hydrostatic pressure

A full-potential linear muffin-tin orbital method (FP-LMTO) based linear-response approach is used to calculate the electron–phonon coupling in Nb under hydrostatic pressure. The superconducting transition temperature Tc is calculated using the Eliashberg equation. The calculated Tc agrees nicely with the experimental result at ambient pressure, but the agreement is only fair at high pressures. The Tc measured anomaly at 60–70 GPa is understood in terms of the 2.5-order Lifshitz transition and its origin is traced back to the qualitative changes in the Fermi surface topology.