Role of van der Waals bonding in layered oxide: Bulk vanadium pentoxide

TL;DR

This study demonstrates that incorporating nonlocal van der Waals interactions via the vdW-DF method in DFT calculations accurately predicts the lattice parameters of bulk V2O5, highlighting the importance of vdW forces in layered oxides.

Contribution

The paper shows that including nonlocal vdW interactions in DFT improves the accuracy of structural predictions for layered oxides like V2O5.

Findings

vdW-DF method stabilizes the bulk structure

Accurate lattice parameters for all three directions

Nonlocal vdW interactions are crucial for layered oxides

Abstract

Sparse matter is characterized by regions with low electron density and its understanding calls for methods to accurately calculate both the van der Waals (vdW) interactions and other bonding. Here we present a first-principles density functional theory (DFT) study of a layered oxide (V2O5) bulk structure which shows charge voids in between the layers and we highlight the role of the vdW forces in building up material cohesion. The result of previous first-principles studies involving semilocal approximations to the exchange-correlation functional in DFT gave results in good agreement with experiments for the two in-plane lattice parameters of the unit cell but overestimated the parameter for the stacking direction. To recover the third parameter we include the nonlocal (dispersive) vdW interactions through the vdW-DF method [Dion et al., Phys. Rev. Lett. 92, 246401 (2004)] testing also various choices of exchange flavors. We find that the transferable first-principle vdW-DF calculations stabilizes the bulk structure. The vdW-DF method gives results in fairly good agreement with experiments for all three lattice parameters.