Application of frozen-phonon method to lattice dynamics in FCC solid iodine

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 omega(L)=231 cm(-1) and omega(T)=159 cm(-1), respectively, at 45 GPa. The phonon frequencies increase with increasing pressure, i.e. omega(L)=260 cm(-1) and omega T=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 chi and D-0: the generalized electronic susceptibility chi is evaluated by utilizing the electron-phonon interaction obtained microscopically on the basis of the tight-binding scheme and the short-range force term D-0 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.