Ab initio electronic structure calculation of hollandite vanadate K$_2$V$_8$O$_{16}$

TL;DR

This study uses ab initio density functional theory calculations to analyze the electronic structure of hollandite vanadate K$_2$V$_8$O$_{16}$, revealing key orbital contributions and the significance of inter-chain coupling and electron correlations.

Contribution

First ab initio study of K$_2$V$_8$O$_{16}$'s electronic states highlighting orbital degeneracies and inter-chain interactions.

Findings

States near Fermi energy are mainly t2g orbitals.

Hybridization with oxygen 2p orbitals is small.

System exhibits significant inter-chain coupling.

Abstract

An \textit{ab initio} electronic structure calculation based on the generalized gradient approximation in the density functional theory is carried out to study the basic electronic states of hollandite vanadate K$_2$V$_8$O$_{16}$. We find that the states near the Fermi energy consist predominantly of the three $t_{2g}$-orbital components and the hybridization with oxygen $2p$ orbitals is small. The $d_{yz}$ and $d_{zx}$ orbitals are exactly degenerate and are lifted from the $d_{xy}$ orbital. The calculated band dispersion and Fermi surface indicate that the system is not purely one-dimensional but the coupling between the VO double chains is important. Comparison with available experimental data suggests the importance of electron correlations in this system.