Dynamic pseudopotential theory of phonon spectra in metals

Electron clouds of large atoms undergo significant distortion during lattice vibration. The shell model, which divides each ion into an inner core and a last-filled electron shell, is combined with the pseudopotential method to provide a theory of phonon spectra. The conduction electrons screen all of the following interactions: core-core, core-shell, and shell-shell. An important feature of the theory is inclusion of exchange interactions of shell electrons with the conduction-electron sea. As a consequence three different dielectric functions appear in the theory (appropriate to core-core, core-shell, and shell-shell interaction energies). The pseudopotential of each ion has two parts: one for the core and one for the shell. The new features of the theory are expected to be important in heavy metals.