A full-potential linear muffin-tin orbital method (FP-LMTO) based linear-re
sponse approach is used to calculate the electron-phonon coupling in Nh und
er hydrostatic pressure. The superconducting transition temperature T-c is
calculated using the Eliashberg equation. The calculated T-c agrees nicely
with the experimental result at ambient pressure, but the agreement is only
fair at high pressures. The T-c measured anomaly at 60-70 GPa is understoo
d in terms of the 2.5-order Lifshitz transition and its origin is traced ba
ck to the qualitative changes in the Fermi surface topology. (C) 2000 Elsev
ier Science B.V. All rights reserved.