Ab Initio Approach for Quantum Magnets with Coupled Cluster and Transcorrelation
Abstract
The nearest-neighbour exchange coupling J1 is the simplest ingredient of model Hamiltonians used to understand magnetism in real materials. Nevertheless, its ab initio determination requires a high-level correlation treatment and a large basis for wave function expansion. Here we compute J1 for five oxygen-bridged spin-1/2 quantum magnets --- Sr2CuO3, La2CuO4, NdNiO2, ZnCu3(OH)6Cl2, and Li2CuO2 --- spanning bridging angles from 180∘ to 94∘ and the crossover from antiferromagnetic to ferromagnetic coupling, using embedded-cluster methodology. To describe the open-shell singlets we use 2-determinant coupled cluster with single and double excitations, which recovers the orbital-breathing enhancement of superexchange from a minimal reference. Basis-set errors are found to be large: extrapolation to the complete basis-set (CBS) limit shifts J1 by up to 50 meV from bases of double-ζ quality. Transcorrelated Hamiltonians reproduce the CBS estimates with modest basis set sizes, yielding an excellent accuracy against experiment at highly affordable cost. These results are the first application of transcorrelated methods in strongly correlated solid-state systems, and establish transcorrelation as a powerful theory in computational research of materials.
Related
- Accelerated "on-the-fly" coupled-cluster path-integral molecular dynamics: Impact of nuclear quantum effects on an asymmetric proton
- Tailored coupled cluster method with sample-based quantum diagonalization: Application to titanium-based metallocene catalytic reactions for 1-hexene production
- Static correlation, a coupled-cluster diagnostic blind spot, and its quantum-computing resolution in silver–dinitrogen clusters
- Nuclear–Electronic Orbital Coupled Cluster Theory with the Nuclear Hartree Product Representation for Multiple Quantum Nuclei and Application to Geometric Isotope Effects
- Microscopic Theory of the Acoustic Faraday Effect in Spin-Orbit Coupled Magnets
BibTeX
@misc{simula2026initio,
title = {{Ab Initio Approach for Quantum Magnets with Coupled Cluster and Transcorrelation}},
author = {Kristoffer Simula and Nikolay A. Bogdanov and Olle Gunnarsson and Daniel Kats and Ali Alavi},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.29324},
eprint = {2610.29324},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.29324},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Ab Initio Approach for Quantum Magnets with Coupled Cluster and Transcorrelation
AU - Kristoffer Simula
AU - Nikolay A. Bogdanov
AU - Olle Gunnarsson
AU - Daniel Kats
AU - Ali Alavi
PY - 2026
DA - 2026/10/21
PB - arXiv
DO - 10.48550/arxiv.2610.29324
UR - https://arxiv.org/abs/2610.29324
AB - The nearest-neighbour exchange coupling J_1 is the simplest ingredient of model Hamiltonians used to understand magnetism in real materials. Nevertheless, its ab initio determination requires a high-level correlation treatment and a large basis for wave function expansion. Here we compute J_1 for five oxygen-bridged spin-1/2 quantum magnets --- Sr_2CuO_3, La_2CuO_4, NdNiO_2, ZnCu_3(OH)_6Cl_2, and Li_2CuO_2 --- spanning bridging angles from 180^∘ to 94^∘ and the crossover from antiferromagnetic to ferromagnetic coupling, using embedded-cluster methodology. To describe the open-shell singlets we use 2-determinant coupled cluster with single and double excitations, which recovers the orbital-breathing enhancement of superexchange from a minimal reference. Basis-set errors are found to be large: extrapolation to the complete basis-set (CBS) limit shifts J_1 by up to 50 meV from bases of double-ζ quality. Transcorrelated Hamiltonians reproduce the CBS estimates with modest basis set sizes, yielding an excellent accuracy against experiment at highly affordable cost. These results are the first application of transcorrelated methods in strongly correlated solid-state systems, and establish transcorrelation as a powerful theory in computational research of materials.
ER -