Fig. 1: Energy Landscape for NdNiO3 as a function of the electronic and ionic lattice disproportionation.
From: Quantifying the role of the lattice in metal–insulator phase transitions

Energy landscape for NdNiO3 as a function of electronic disproportionation ΔN and lattice distortion (bond disproportionation) Q as obtained from the energy functional methods introduced in this paper using data from ref. 4.