Ab Initio Wavefunction Analysis of Electron Removal Quasi-Particle State of NdNiO2 With Fully Correlated Quantum Chemical Methods

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Katukuri, VM 
Bogdanov, NA 
Alavi, A 

jats:pThe discovery of superconductivity in hole-doped infinite-layer NdNiOjats:sub2</jats:sub> — a transition metal (TM) oxide that is both isostructural and isoelectronic to cuprate superconductors—has lead to renewed enthusiasm in the hope of understanding the origin of unconventional superconductivity. Here, we investigate the electron-removal states in infinite-layered Nijats:sup1+</jats:sup> oxide, NdNiOjats:sub2</jats:sub>, which mimics hole doping, with the state-of-the-art many-body multireference quantum chemistry methods. From the analysis of the many-body wavefunction we find that the hole-doped jats:italicd</jats:italic>jats:sup8</jats:sup> ground state of NdNiOjats:sub2</jats:sub> is very different from the jats:italicd</jats:italic>jats:sup8</jats:sup> ground state in isostructural cuprate analog CaCuOjats:sub2</jats:sub>, although the parent jats:italicd</jats:italic>jats:sup9</jats:sup> ground states are for the most part identical. We show that the doped hole in NdNiOjats:sub2</jats:sub> mainly localizes on the Ni 3jats:inline-formula<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="m1">mml:msubmml:mrowmml:mid</mml:mi></mml:mrow>mml:mrowmml:msupmml:mrowmml:mix</mml:mi></mml:mrow>mml:mrowmml:mn2</mml:mn></mml:mrow></mml:msup>mml:mo−</mml:mo>mml:msupmml:mrowmml:miy</mml:mi></mml:mrow>mml:mrowmml:mn2</mml:mn></mml:mrow></mml:msup></mml:mrow></mml:msub></mml:math></jats:inline-formula> orbital to form a closed-shell singlet, and this singlet configuration contributes to ∼40% of the wavefunction. In contrast, in CaCuOjats:sub2</jats:sub> the Zhang-Rice singlet configurations contribute to ∼65% of the wavefunction. With the help of the quantum information concept of entanglement entropy, we quantify the different types of electronic correlations in the nickelate and cuprate compounds, and find that the dynamic radial-type correlations within the Ni jats:italicd</jats:italic> manifold are persistent in hole-doped NdNiOjats:sub2</jats:sub>. As a result, the jats:italicd</jats:italic>jats:sup8</jats:sup> multiplet effects are stronger and the additional hole foot-print is more three-dimensional in NdNiOjats:sub2</jats:sub>. Our analysis shows that the most commonly used three-band Hubbard model employed to express the doped scenario in cuprates represents ∼90% of the jats:italicd</jats:italic>jats:sup8</jats:sup> wavefunction for CaCuOjats:sub2</jats:sub>, but such a model grossly approximates the jats:italicd</jats:italic>jats:sup8</jats:sup> wavefunction for NdNiOjats:sub2</jats:sub> as it only stands for ∼60% of the wavefunction.</jats:p>

nickelates, superconductors, wavefunction quantum chemistry, doped-holes, ab initio
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Frontiers in Physics
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Frontiers Media SA