Fig. 3: Equation of state fit for bulk rare-earth nickelates, and corresponding electronic and total energies.
From: Quantifying the role of the lattice in metal–insulator phase transitions
a Points: Electronic disproportionation as a function of bond disproportionation ΔN(Q) values used for the three RNiO3 materials as obtained from Density Functional Theory + Dynamical Mean Field Theory calculations from ref. 6; Light lines: fits of the points to Eq. 7. Also shown is the Q(ΔN) line obtained from the Q equation of state Eq. 2. Note that the ratio of the lattice stiffness to the linear coupling K/g has the same value for all three materials. b Electronic energy, c total energy Ftot = F of three RNiO3 compounds as a function of electronic order parameter ΔN, minimized over structural order parameter (bond disproportionation) Q. d Total energy as function of lattice distortion Q, minimized over ΔN. Energies per 10 atom unit cell.
