The electronic structure of hollandite ruthenate ${\mathrm{K}}_2$Ru${}_8$O${}_{16}$ is calculated using the generalized gradient approximation (GGA) in the density functional theory, where the Hubbard-type repulsive interaction is taken into account (GGA$+$$U$). We find that the electronic structure near the Fermi level consists only of a single band coming predominantly from the $4d_{\mathit{yz}}$ and $4d_{\mathit{zx}}$ orbitals of Ru ions with a strong admixture of the $2p_z$ orbitals of corner-shared O ions connecting the double RuO chains. The band structure near the Fermi level is highly quasi-one-dimensional, exactly at half filling, and has a pair of two nearly parallel sheetlike Fermi surfaces separated by $\pi /c$. The calculated results are consistent with observed quasi-one-dimensional transport properties of the material. These results establish that ${\mathrm{K}}_2$Ru${}_8$O${}_{16}$ belongs to a class of possible Tomonaga-Luttinger-liquid materials.

• Received 16 March 2011

DOI:https://doi.org/10.1103/PhysRevB.83.195101