Influence of local electron interactions on phonon spectrum in iron

Abstract

The density functional generalized-gradient approximation with the local Coulomb interaction $U$ and the direct method have been applied to study the electronic structure and the phonon spectrum of Fe $\ensuremath{\alpha}$ bcc phase. The electronic structure, the equilibrium lattice constant, as well as phonon frequencies and phonon density of states are found to depend primarily on the interaction between the electrons of equal spin $U\ensuremath{-}J$, where $J$ is Hund's exchange element. We have found that the results of the present ab initio calculations reproduce quite well the phonon density of states obtained from inelastic neutron scattering for $U\ensuremath{\simeq}1.0\phantom{\rule{0.3em}{0ex}}\mathrm{eV}$ and $J\ensuremath{\simeq}0.5\phantom{\rule{0.3em}{0ex}}\mathrm{eV}$, suggesting a considerable screening of local Coulomb interactions in iron.