Predicted Superconductive Properties of Lithium under Pressure

A superconducting state of lithium has not been found at ambient pressure, but the present theoretical work shows that high values of the critical temperature, $T_c$, may be expected for some high-pressure phases. Ab initio electronic structure calculations are used to calculate the electron-phonon coupling in a “rigid-muffin-tin approximation,” and estimates using McMillan's formula suggest that under increasing pressure $T_c$ in fcc-Li may reach 50–70 K before transitions occur to the rhombohedral $\left(\mathrm{hR}1\mathrm{}-\mathrm{Li}\right)$ and subsequently to the $\mathrm{cI}16\mathrm{}-\mathrm{Li}$ phase near 40 GPa. In $\mathrm{cI}16\mathrm{}-\mathrm{Li}$ $T_c$ may reach a maximum in the range 60–80 K.