Pressure Effects on Electronic Structure and Electron-Lattice Interaction of Cubic Phase of Solid Iodine

Band structure calculations based on the full-potential linearized augmented-plane-wave method are performed for the metallic FCC phase of solid iodine. Pressures which are evaluated from the total energy as a function of the atomic volume agree well with the observations. The calculated Hall coefficients are positive and agree in order of magnitude with the experimental data. Contradicting with the observations, however, they decrease slowly as pressure increases. Pressure effects on the electron-lattice interaction are studied microscopically on the basis of the tight-binding scheme. The magnitude of the transfer integrals and their derivatives increase significantly with increasing pressure. As the results the McMillan-Hopfield parameter N(E_F)〈ξ²〉 increase with increasing pressure, which indicates a possibility of increase of the superconducting transition temperature with increasing pressure. Here N(E_F) denotes the desnity of states at the Fermi level and 〈ξ²〉 is the Fermi surface average of squaure of electron-phonon coupling.