Multiconfigurational Analysis of Local Electronic Structure of RuO2 Using Relativistic Embedded Clusters
Abstract
We present a multiconfigurational, relativistic embedded-cluster study of the local electronic structure of ruthenium dioxide (RuO2), a candidate altermagnetic material. Starting from free Ru ions, we progressively build up the local environment through a Ru+Q6 electrostatic model, a bare [RuO6]8− ligand model, and finally a high-accuracy RuO6@CTEP embedded cluster that reproduces the crystalline surroundings. All systems are treated at the SA-CASSCF and NEVPT2+SOC levels of theory to capture strong electron correlation and spin-orbit coupling on an equal footing. While the formal local site symmetry of the Ru sites in RuO2 is orthorhombic (D2h), we find that the calculated 4d-orbital energy spectrum and its splitting pattern behave much closer to the higher tetragonal (D4h) symmetry, preserving a strong quasi-degeneracy among the relevant 4d orbitals. Since the local xy quadrupolar order responsible for altermagnetic spin splitting in independent-particle models relies on this symmetry reduction, its suppression by orbital quasi-degeneracy offers a natural explanation for why altermagnetism is not observed in bulk RuO2 experiments, in contrast to the robust altermagnetic signatures reported in strained thin films.
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BibTeX
@misc{i2026multiconfigurational,
title = {{Multiconfigurational Analysis of Local Electronic Structure of $\mathrmRuO_2$ Using Relativistic Embedded Clusters}},
author = {Zhosan I. A. and Lomachuk Yu. V. and Maltsev D. A. and Moiseev I. A. and Andreev O. Yu},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.20526},
eprint = {2609.20526},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.20526},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Multiconfigurational Analysis of Local Electronic Structure of RuO_2 Using Relativistic Embedded Clusters
AU - Zhosan I. A.
AU - Lomachuk Yu. V.
AU - Maltsev D. A.
AU - Moiseev I. A.
AU - Andreev O. Yu
PY - 2026
DA - 2026/09/17
PB - arXiv
DO - 10.48550/arxiv.2609.20526
UR - https://arxiv.org/abs/2609.20526
AB - We present a multiconfigurational, relativistic embedded-cluster study of the local electronic structure of ruthenium dioxide (RuO_2), a candidate altermagnetic material. Starting from free Ru ions, we progressively build up the local environment through a Ru+Q_6 electrostatic model, a bare [RuO_6]^8− ligand model, and finally a high-accuracy RuO_6@CTEP embedded cluster that reproduces the crystalline surroundings. All systems are treated at the SA-CASSCF and NEVPT2+SOC levels of theory to capture strong electron correlation and spin-orbit coupling on an equal footing. While the formal local site symmetry of the Ru sites in RuO_2 is orthorhombic (D_2h), we find that the calculated 4d-orbital energy spectrum and its splitting pattern behave much closer to the higher tetragonal (D_4h) symmetry, preserving a strong quasi-degeneracy among the relevant 4d orbitals. Since the local xy quadrupolar order responsible for altermagnetic spin splitting in independent-particle models relies on this symmetry reduction, its suppression by orbital quasi-degeneracy offers a natural explanation for why altermagnetism is not observed in bulk RuO_2 experiments, in contrast to the robust altermagnetic signatures reported in strained thin films.
ER -