  We demonstrate how first-principles calculations of many competing low-energy
states of a correlated material, here a cuprate, can be used to develop a
thermodynamic model of Mott and pseudogap transitions in terms of magnetic
short-range order. Mott physics is found in this picture to be driven by an
unbinding of the antiphase domain walls, while the pseudogap phenomenon
represents local moment formation. We provide explanations for nematicity and
Fermi arc formation, and find a striking correspondence with many-body
perturbation theory predictions.
