Charge transfer in Rb-intercalated graphites

Charge transfer in stage-1 and stage-2 Rb graphite intercalation compounds was analyzed in terms of total electron-density distributions. The net charge transfer was decomposed into geometrical and ``physical'' components, obtained by the integration of reference and difference charge densities [nref(r) and {δ}n(r)=n(r)-nref(r)], respectively, over regions associated with the host or the intercalant. The reference charge density is the superposition of charge densities for the host and intercalant sublattices treated separately, and the host-intercalant partitioning is defined by the condition that the normal component of the density gradient vanish at the interface. Employing self-consistent local-density-functional-theory calculations based on separable pseudopotentials and a plane-wave basis, we obtained a physical charge transfer of 0.2 (0.35)e and a geometrical charge transfer of 0.55e, which yield a net charge transfer of 0.75 (0.90)e for stage 1 (2).