The electron-phonon coupling parameter e-ph, while playing a centrally important role in superconductivity and other phenomena, is still a difficult quantity to determine from first-principles theory. The availability of accurate ab initio self-consistent energy-band calculations of partial and total density of states (DOS) allows to be determined from the electronic specific heat or from simple theoretical treatments such as the rigid-ion approximation. We have assessed the accuracy of these determinations (and the band-structure results) in a number of transition metals and A15 and C15 intermetallic compounds. We include comparisons with results obtained with the use of the McMillan-equation parametrization of Tc along with experimental results from tunneling measurements, NMR, and comparisons of high- and low-T specific-heat data. The results of these comparisons show that for many of the high-DOS materials, serious discrepancies exist between the theoretical and experimental determinations. The role of spin fluctuations and lattice transformations is discussed in connection with these results.
ASJC Scopus subject areas
- Condensed Matter Physics