Abstract
Structural phase transitions and superconducting properties in three phases (, fcc, and ) of solid Li are investigated using a pseudopotential plane-wave method based on density functional perturbation theory. In particular, it is shown that phonon softening is responsible for a pressure-induced transition as well as for a significant enhancement of electron-phonon coupling and superconducting transition temperature preceding this structural transformation. The nature of superconductivity in the fcc and phases is examined by solving the Eliashberg equations with the spectral function obtained from first-principles calculations and by evaluating the functional derivative . The calculated reaches a maximum at pressure close to the transition and is significantly reduced in the phase, in agreement with the trend observed experimentally. The variation in as a function of pressure is explained in terms of the functional derivative and shifts of the spectral weight.
8 More- Received 16 December 2008
DOI:https://doi.org/10.1103/PhysRevB.79.054524
©2009 American Physical Society