Simultaneous Spin and Point-Group Adaptation in Exact Diagonalization of Spin Clusters

While either a spin or point-group adaptation is straightforward when considered independently, the standard technique for factoring isotropic spin Hamiltonians by the total spin <i>S</i> and the irreducible representation <inline-formula><math xmlns="http://www.w3.org/1998...

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Bibliographic Details
Main Authors: Shadan Ghassemi Tabrizi, Thomas D. Kühne
Format: Article
Language:English
Published: MDPI AG 2025-03-01
Series:Magnetism
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Online Access:https://www.mdpi.com/2673-8724/5/1/8
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Summary:While either a spin or point-group adaptation is straightforward when considered independently, the standard technique for factoring isotropic spin Hamiltonians by the total spin <i>S</i> and the irreducible representation <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mi mathvariant="sans-serif">Γ</mi></semantics></math></inline-formula> of the point group is limited by the complexity of the transformations between different coupling schemes that are related in terms of their site permutations. To overcome these challenges, we apply projection operators directly to uncoupled basis states, enabling the simultaneous treatment of spin and point-group symmetry without the need for recoupling transformations. This provides a simple and efficient approach for the exact diagonalization of isotropic spin models, which we illustrate, with applications in Heisenberg spin rings and polyhedra, including systems that are computationally inaccessible with conventional coupling techniques.
ISSN:2673-8724