Computing the properties of the rare-earth nickelates via DFT+DMFT

Chris Marianetti (Columbia University)

Despite the many successes of density functional theory (DFT), it is known to qualitatively break down when describing certain aspects of strongly correlated electron materials, including both electronic and structural failures. These deficiencies can be remedied with a dual variable theory which combines DFT and the dynamical mean-field theory (ie. DFT+DMFT). Here we apply DFT+DMFT to the structural and metal-insulator transitions of the rare-earth nickelate perovskites as a function of rare earth ion, pressure, and temperature. In contrast to previous DFT and DFT+U theories, the present method accounts for the experimentally observed structure of LaNiO3 and the insulating nature of the other perovskites and quantitatively reproduces the metal-insulator and structural phase diagram in the plane of pressure and rare earth element. The temperature dependence of the energetics of the phase transformation indicates that the thermal transition is driven by phonon entropy effects.

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