Everything Everywhere All at Once: Strong Correlations from Hidden Symmetry Breaking in Dynamical Mean-Field Theory

by Alberto Carta (PSI)

Wednesday 13 May 2026, 15:00 → 16:00 Europe/Zurich

OVGA/200

DFT+U can effectively describe paramagnetic Mott insulators by artificially imposing a single magnetic or orbital order. This static proxy works remarkably well, but it obscures the true many-body nature, and it is thought to fail to capture genuine spectral features such as Hubbard bands.

We introduce the thermal dephased ensemble (TDE), which extends DFT+U by averaging over the landscape of all competing static DFT+U solutions. We show that for many realistic Mott insulators, this simple extension restores the paramagnetic symmetry and produces results matching numerically exact DMFT results for NiO and FeO, while retaining the computational simplicity of static mean-field calculations.

Conceptually, TDE demonstrates that the "strong correlations" in these insulators are largely a manifestation of classical configurational entropy among symmetry-broken local states, taking a first step towards bridging the gap between Alex Zunger’s polymorphous, yet static, view of a material and DMFT’s dynamical picture. The approach offers a controlled path to systematically include further quantum fluctuations.

Alberto Carta,  Hugo R. Strand, Michael Schüler and Nicola Marzari