A first-principles density-functional description of the electronic structures of the high-T c cuprates has remained a long-standing problem since their discovery in 1986, with calculations failing to capture either the insulating (magnetic) state of the pristine compound or the transition from the insulating to metallic state with doping. Here, by taking lanthanum cuprate as an exemplar high-T c cuprate, we show that the recently developed non-empirical, strongly constrained and appropriately normed density functional accurately describes both the antiferromagnetic insulating ground state of the pristine compound and the metallic state of the doped system. Our study yields new insight into the low-energy spectra of cuprates and opens up a pathway toward wide-ranging first-principles investigations of electronic structures of cuprates and other correlated materials.

We show how an accurate first-principles treatment of the antiferromagnetic (AFM) ground state of La2CuO4 can be obtained without invoking any free parameters such as the Hubbard U . The magnitude and orientation of our theoretically predicted magnetic moment of 0.495µB on Cu-sites along the (100) direction are in excellent accord with experimental results. The computed values of the band gap (1.00 eV) and the exchange-coupling (-138 meV) match the corresponding experimental values. We identify interesting band splittings below the Fermi energy, including an appreciable Hund's splitting of 1.25 eV. The magnetic form factor obtained from neutron scattering experiments is also well described by our calculations. Our study opens up a new pathway for first-principles investigations of electronic and atomic structures and phase diagrams of cuprates and other complex materials.arXiv:1808.06283v1 [cond-mat.str-el]

Vertically-stacked 2D materials produce new physics from interfacial orbital interactions and the moiré superlattice, possibly inducing the formation of a robust real-space, non-atomic charge lattice at room temperature.