Electronic structure α'-NaV2O5: Wave-function-based embedded-cluster calculations

Results of ab initio embedded-cluster calculations indicate that the doublet ground state of the V-OR-V rung originates from a V 3dxy1–OR2py1–V 3dxy1 configuration. In the high temperature undistorted geometry the unpaired electron on oxygen is low-spin coupled to the 3d electrons and spin density is equally distributed over the vanadium ions. Based on this picture of the electronic ground state we propose a mechanism for the phase transition at 34 K. We find that a symmetry-broken configuration, R(Vi-OR)