DFT Trends in the Electronic Structure and Magnetic Properties of Reduced Ruddlesden-Popper Nickelates

In this chapter, we present our electronic structure calculations based on density-functional theory for the series of layered nickelates \(R_{n+1}\) Ni \({ }_{n}\) O \({ }_{2n+2}\) ( \(n=\infty \) and 3–6). We focus in particular on the \(n=4\) –6 nickelates as they fall into the superconducting dome of the cuprates in terms of electron count. We concentrate on understanding the similarities and differences of their electronic structure to the cuprates as well as on comparing them to the already studied trilayer \((n=3)\) and infinite-layer nickelates ( \(n=\infty \) ). From our calculations, we find that the cuprate-like character of layered nickelates increases from the \(n = \infty \) to the \(n = 3\) members as the charge transfer energy and the self-doping effect due to \(R(5d)\) bands around the Fermi level gradually decrease. This chapter is based on results published in Phys. Rev. B 102, 224506 (2020) , Phys Rev. B 104, 035148 (2021) , and Sci. Rep. 12, 17864 (2022) .