Effect of the electronic charge gap on LO bond-stretching phonons in undoped La$_2$CuO$_4$ calculated using LDA+U

Tyler C. Sterling; Dmitry Reznik

doi:10.1103/PhysRevB.104.134311

paper

Effect of the electronic charge gap on LO bond-stretching phonons in undoped La $_{2}$ CuO $_{4}$ calculated using LDA+U

arXiv:2110.10274 · doi:10.1103/PhysRevB.104.134311

Abstract

Typical density-functional theory calculations that wrongly predict undoped cuprates to be metallic also predict Cu-O half- and full-breathing phonon energies that are significantly softer than observed, presumably because of weak on-site Coulomb repulsion on the Cu 3d orbitals. We used DFT+U calculations with antiferromagnetic supercells of La $_{2}$ CuO $_{4}$ to establish correlation between the on-site repulsion strength, tuned via adjusting the value of U, and phonon dispersions. We find that breathing and half-breathing phonons reach experimental values when U is tuned to obtain the correct optical gap and magnetic moments. We demonstrate that using distorted supercells within DFT+U is a promising framework to model phonons in undoped cuprates and other perovskite oxides with complex, interrelated structural and electronic degrees of freedom.

8 pages, 6 figures

Effect of the electronic charge gap on LO bond-stretching phonons in undoped La2​CuO4​ calculated using LDA+U

Abstract

References in corpus (16)

Effect of the electronic charge gap on LO bond-stretching phonons in undoped La $_{2}$ CuO $_{4}$ calculated using LDA+U