抄録
First-principles frozen-phonon calculations based on the full-potential linearized augmented-plane-wave method are performed for the X point phonon modes of the high-pressure FCC phase of solid iodine. The longitudinal and the transverse phonon frequencies have been evaluated to be ωL=231 cm-1 and ωT=159 cm-1, respectively, at 45 GPa. The phonon frequencies increase with increasing pressure, i.e. ωL=260 cm-1 and ωT=179 cm-1 at 64 GPa. The phonon frequencies in the whole Brillouin zone are calculated by expressing the dynamical matrix as the sum of χ and D0: the generalized electronic susceptibility χ is evaluated by utilizing the electron-phonon interaction obtained microscopically on the basis of the tight-binding scheme and the short-range force term D0 is determined so as to reproduce the X point phonon frequencies obtained by the frozen-phonon method. Pressure effects on the superconductivity of FCC iodine are discussed by using the obtained results.
