First-principles calculation of lattice dynamics and electron-phonon interaction in high pressure phase of solid iodine

Abstract

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 which becomes a superconductor at T ∼ 1K. The longitudinal and the transverse phonon frequencies have been evaluated to be ω L = 231 cm −1 and ω T = 159 cm −, respectively, at 45 GPa. The phonon frequencies increase with increasing pressure. For example, we have obtained ω L = 260 cm −1 and ω T = 179 cm −1 at 64 GPa. The electron-phonon interaction is evaluated microscopically on the basis of the tight-binding scheme and then the phonon frequencies are calculated in the whole Brillouin zone by introducing appropriate short-range force constants. The results obtained are discussed in connection with pressure effects on superconductivity of FCC iodine.