SCREENING OF THE SHORT-RANGE POTENTIAL BY THE LOCAL FIELD CORRECTION IN THE LATTICE DYNAMICS OF VANADIUM

Abstract
The dielectric formulation of the local field correction to the dynamical matrix for phonon dispersion relation in d-band metals in the transition-metal model potential approximation is re-examined, with a view to explore its influence on the shortrange (Born-Mayer) interatomic force contribution to the dynamical matrix. It is observed that the off-diagonal components of the inverse dielectric matrix, which determine the local field correction, make contributions that tend to cancel or "screen" the Born-Mayer contribution, just as the diagonal components of the inverse dielectric matrix tend to provide screening of the long range (Coulombic) contribution. Numerical calculation for vanadium shows that the cancellation of the Born-Mayer contribution to the dynamical matrix by the local field correction is physically significant, and leads to a better understanding of the soft modes in the phonon spectra of body-centered cubic transition metals.