The interplay between the structural and magnetic properties of vanadium dioxide from first principles

The effects of the spin and lattice degrees of freedom on the electronic structure of M1 vanadium dioxide are explored using a quasiparticle description. Contraction of the inter-vanadium spacing of the Peierls pairings stabilizes bonding electrons, reducing polarizability and thus widening the band gap. Increases of this inter-vanadium spacing of as little as 1 \% reduce this stabilization, resulting in a crossover to ferromagnetic behaviour accomplished by half of the valence electrons inhabiting the leading edge of the conduction band in localized atomic-like orbitals, as the antiferromagnetic order becomes unstable with respect to rearrangement according to Hund's first rule. The data indicates that the magnetic structure of M1 vanadium dioxide may be finely balanced; the antiferromagnetic order is a consequence of the overlapping nuclear potential of the Peierls pairs, and input which disrupts this will have a significant effect on magnetic properties.