A Scalable Translationally Invariant Variational Theory of Ab Initio Polarons
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arXiv
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| Format: | Preprint |
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2026
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| _version_ | 1866909020353200128 |
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| author | Baumgarten, Moritz K. A. Wu, Hamlin Jiang, Tong Lee, Joonho |
| author_facet | Baumgarten, Moritz K. A. Wu, Hamlin Jiang, Tong Lee, Joonho |
| contents | We introduce a scalable, translationally invariant variational theory for ab initio polarons that remains applicable across coupling regimes without resorting to supercells. Our approach combines a momentum-projected Toyozawa-type wavefunction with a low-rank factorization of the electron-phonon kernel, enabling near-linear scaling with the number of $\mathbf{k}$-points while capturing both delocalized and self-trapped carriers. Benchmarks for the Fröhlich model, LiF, and anatase and rutile TiO$_2$ yield accurate polaron binding energies, thermodynamic-limit band structures, and transparent real-space measures of polaron extent. For LiF, comparison with first-principles diagrammatic Monte Carlo (DiagMC) reveals close agreement for the weak-coupling electron-polaron ground state and band structure. However, in the hole-polaron of LiF, which is in the strong-coupling regime, we found a significant bias in DiagMC results. These results establish momentum-projected variational wavefunctions as a systematically improvable route to thermodynamic limit studies of polarons in real materials. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2605_05675 |
| institution | arXiv |
| publishDate | 2026 |
| record_format | arxiv |
| spellingShingle | A Scalable Translationally Invariant Variational Theory of Ab Initio Polarons Baumgarten, Moritz K. A. Wu, Hamlin Jiang, Tong Lee, Joonho Materials Science Chemical Physics Computational Physics We introduce a scalable, translationally invariant variational theory for ab initio polarons that remains applicable across coupling regimes without resorting to supercells. Our approach combines a momentum-projected Toyozawa-type wavefunction with a low-rank factorization of the electron-phonon kernel, enabling near-linear scaling with the number of $\mathbf{k}$-points while capturing both delocalized and self-trapped carriers. Benchmarks for the Fröhlich model, LiF, and anatase and rutile TiO$_2$ yield accurate polaron binding energies, thermodynamic-limit band structures, and transparent real-space measures of polaron extent. For LiF, comparison with first-principles diagrammatic Monte Carlo (DiagMC) reveals close agreement for the weak-coupling electron-polaron ground state and band structure. However, in the hole-polaron of LiF, which is in the strong-coupling regime, we found a significant bias in DiagMC results. These results establish momentum-projected variational wavefunctions as a systematically improvable route to thermodynamic limit studies of polarons in real materials. |
| title | A Scalable Translationally Invariant Variational Theory of Ab Initio Polarons |
| topic | Materials Science Chemical Physics Computational Physics |
| url | https://arxiv.org/abs/2605.05675 |