Abstract
Rare-earth trihydride (RH3) compounds exhibit intriguing coupled electronic and structural properties as a function of doping, hydrogen vacancies, and thermodynamic conditions. Theoretical studies of these materials typically rely on density functional theory (DFT), including the use of small supercells that may underestimate strong correlation effects and structural distortions which in turn may influence their metallicity. Here, we elucidate the roles of lattice distortions and correlation effects on the electronic properties of pristine and doped RH3 compounds by adopting DFT+U and quantum Monte Carlo (QMC) methods. Linear-response constrained DFT (LR-cDFT) methods find Hubbard U ≈2 eV for Rd orbitals and U≈6 eV for Hs/Np/Op orbitals. The small U on Lud orbitals is consistent with QMC calculations on LuH3 and LuH2.875N0.125. In pure face-centered-cubic (FCC) RH3 (R=Lu,Y) compounds, neither DFT nor DFT+U with the self-consistently determined U is enough to create a band gap, however a supercell with hydrogen distortions creates a small gap whose magnitude increases when performing DFT+U with self-consistently determined U values. Correlation effects, in turn, have a moderate influence on the coupled structural and electronic properties of doped RH3 compounds and may be important when considering the competition between structural distortions and superconductivity.
| Original language | English |
|---|---|
| Article number | 195137 |
| Journal | Physical Review B |
| Volume | 111 |
| Issue number | 19 |
| DOIs | |
| State | Published - May 15 2025 |
Funding
Authors are grateful to Benjamin Kincaid, Haihan Zhou, Abdulgani Annaberdiyev, and Lubos Mitas for optimizing Lu ccECP. This research was supported by the National Science Foundation (DMR-2104881, R.J.H.), the Department of Energy (DOE) National Nuclear Security Administration through the Chicago/DOE Alliance Center (DE-NA0004153; A.D., R.J.H.), the DOE Office of Science (DE-SC0020340, R.J.H.), and NSF SI2-SSE Grant 1740112 (H.P.). This research used resources of the National Energy Research Scientific Computing Center (NERSC), a U.S. Department of Energy Office of Science User Facility located at Lawrence Berkeley National Laboratory, operated under Contract No. DE-AC02-05CH11231 using NERSC award BES-ERCAP0023615. H.S. and P.G. (QMC calculations) were supported by the U.S. Department of Energy, Office of Science, Basic Energy Sciences, Materials Sciences and Engineering Division, as part of the Computational Materials Sciences Program and Center for Predictive Simulation of Functional Materials. An award of computer time was provided by the Innovative and Novel Computational Impact on Theory and Experiment (INCITE) program. Some part of DFT-based research was conducted as part of a user project at the Center for Nanophase Materials Sciences (CNMS), which is a US Department of Energy, Office of Science User Facility at Oak Ridge National Laboratory. Some contributions to the manuscript has been sponsored by UT-Battelle, LLC under Contract No. DE-AC05-00OR22725 with the U.S. Department of Energy. The United States Government retains and the publisher, by accepting the article for publication, acknowledges that the United States Government retains a non-exclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this manuscript, or allow others to do so, for United States Government purposes. The Department of Energy will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan .