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]

Electrification of heavy-duty transport and aviation requires a paradigm shift in electrode 1 materials and anionic redox represents one possible approach to meeting these demanding targets. However, questions on the validity of the O 2− /O − oxygen redox paradigm remain open and alternative explanations for the origin of the anionic capacity have been proposed because electronic orbitals associated with redox reactions cannot be measured by standard experiments. Here, by using high energy x-ray Compton measurements along with firstprinciples modeling, we show how the electronic orbital that lies at the heart of the reversible and stable anionic redox activity can be imaged and visualized and its character and symmetry can be determined. Differential changes in the Compton profile with Li concentration are shown to be sensitive to the phase of the electronic wave function and carry signatures of electrostatic and covalent bonding effects. Our study not only provides a picture of the workings of a lithium-rich battery at the atomic scale but also suggests pathways for improving existing cathodes and designing new ones.