  The electronic structure of Sr0.35CoO2, structurally analogous to the layered
NaxCoO2, has been evaluated using the local spin density approximation (LSDA).
We find that evident c-dispersions appear in both the e'g and a1g Co-derived
bands, demonstrating the existence of a notable interplanar interaction in
Sr0.35CoO2. The LSDA+U calculation reveals that the electronic structure, in
particular the band splitting between the spin-up and spin-down electrons,
changes evidently along with the increase of the effective on-site Coulomb
interaction U. Analysis of theoretical and experimental electron energy-loss
spectra (EELS) for the oxygen K-edge and the Co L23-edge suggests that the
on-site interaction (U) in Sr0.35CoO2 is less than 3eV which is noticeably
weaker than the estimated value (from 5eV to 8eV) in the NaxCoO2 materials.
