Noninteracting-spin band model for dielectric screening and local field corrections in ferromagnetic nickel

摘要: The diagonal and the nondiagonal parts of dielectric matrix are evaluated for ferromagnetic nickel using a noninteracting-spin band model which is constructed with help detailed band-structure calculations Callaway Wang. free-electron approximation used electrons in $s$ band, while simple tight-binding wave function $d$ subbands. part performed field vector $\stackrel{\ensuremath{\rightarrow}}{\mathrm{q}}$ along three principal symmetry directions [100], [110], [111] anisotropy found to be quite small. Outside first Brillouin zone, only [001] direction both parts. contribution minority-spin ($\ensuremath{\downarrow}$) bands much larger as compared majority-spin ($\ensuremath{\uparrow}$) bands. Away from vicinity $\stackrel{\ensuremath{\rightarrow}}{\mathrm{q}}=0$ due interband transitions smaller intraband transitions. part, i.e., local-field corrections 50% intermediate values $|\stackrel{\ensuremath{\rightarrow}}{\mathrm{q}}+\stackrel{\ensuremath{\rightarrow}}{\mathrm{G}}|$, where $\stackrel{\ensuremath{\rightarrow}}{\mathrm{G}}$ reciprocal-lattice vector. total also results paramagnetic phase it that slightly phase.