Breakdown of broken-symmetry approach to exchange interaction
Iwahara, Naoya; Huang, Zhishuo; Mansikkamäki, Akseli; Chibotaru, Liviu F. (2025-04-22)
American institute of physics
22.04.2025
Naoya Iwahara, Zhishuo Huang, Akseli Mansikkamäki, Liviu F. Chibotaru; Breakdown of broken-symmetry approach to exchange interaction. J. Chem. Phys. 28 April 2025; 162 (16): 164701. https://doi.org/10.1063/5.0255897
https://rightsstatements.org/vocab/InC/1.0/
© 2025 Author(s). Published under an exclusive license by AIP Publishing. This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. This article appeared in Naoya Iwahara, Zhishuo Huang, Akseli Mansikkamäki, Liviu F. Chibotaru; Breakdown of broken-symmetry approach to exchange interaction. J. Chem. Phys. 28 April 2025; 162 (16): 164701. https://doi.org/10.1063/5.0255897 and may be found at https://pubs.aip.org/aip/jcp/article/162/16/164701/3344883/Breakdown-of-broken-symmetry-approach-to-exchange.
https://rightsstatements.org/vocab/InC/1.0/
© 2025 Author(s). Published under an exclusive license by AIP Publishing. This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. This article appeared in Naoya Iwahara, Zhishuo Huang, Akseli Mansikkamäki, Liviu F. Chibotaru; Breakdown of broken-symmetry approach to exchange interaction. J. Chem. Phys. 28 April 2025; 162 (16): 164701. https://doi.org/10.1063/5.0255897 and may be found at https://pubs.aip.org/aip/jcp/article/162/16/164701/3344883/Breakdown-of-broken-symmetry-approach-to-exchange.
https://rightsstatements.org/vocab/InC/1.0/
Julkaisun pysyvä osoite on
https://urn.fi/URN:NBN:fi:oulu-202504242899
https://urn.fi/URN:NBN:fi:oulu-202504242899
Tiivistelmä
Abstract
Broken-symmetry (BS) approaches are widely employed to evaluate Heisenberg exchange parameters, primarily in combination with DFT calculations. For many magnetic materials, BS-DFT calculations give reasonable estimations of exchange parameters, although systematic failures have also been reported. While the latter were attributed to deficiencies of approximate exchange–correlation functional, we prove here by treating a simple model system that the broken-symmetry methodology has serious problems. Detailed analysis clarifies the intrinsic issue with the broken-symmetry treatment of low-spin states. It shows, in particular, that the error in the BS calculation of exchange parameter scales with the degree of covalency between the magnetic and the bridging orbitals. This is due to the constraint on the form of multiconfigurational state imposed by the BS determinant, a feature common to other single-reference methods too. As a possible tool to overcome this intrinsic drawback of single-determinant BS approaches, we propose their extension to a minimal multiconfigurational version.
Broken-symmetry (BS) approaches are widely employed to evaluate Heisenberg exchange parameters, primarily in combination with DFT calculations. For many magnetic materials, BS-DFT calculations give reasonable estimations of exchange parameters, although systematic failures have also been reported. While the latter were attributed to deficiencies of approximate exchange–correlation functional, we prove here by treating a simple model system that the broken-symmetry methodology has serious problems. Detailed analysis clarifies the intrinsic issue with the broken-symmetry treatment of low-spin states. It shows, in particular, that the error in the BS calculation of exchange parameter scales with the degree of covalency between the magnetic and the bridging orbitals. This is due to the constraint on the form of multiconfigurational state imposed by the BS determinant, a feature common to other single-reference methods too. As a possible tool to overcome this intrinsic drawback of single-determinant BS approaches, we propose their extension to a minimal multiconfigurational version.
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