Exactness of Symmetry-Broken Self-Interaction Correction in the Strongly-Correlated or Classical Limit: Harmonium as a Demonstration
Abstract
Strong electron correlation is an important challenge to both wavefunction and density functional theory. It has been argued that the Perdew-Zunger 1981 self-interaction correction to any density functional approximation, after symmetry breaking, can correctly describe the ground-state energy in the strongly-correlated limit in which each electron is described by a highly-localized and non-overlapped one-electron spin orbital. It has also been argued that the classical limit, in which Planck's constant tends to zero, is the strongly-correlated limit of quantum mechanics, where standard density functionals fail badly, as demonstrated by the exactly-solvable problem of harmonium (two Coulomb-interacting electrons bound by a spherically-symmetric harmonic-oscillator external potential). Here we combine these two ideas and demonstrate that, for harmonium, symmetry-broken self-interaction correction is exact in the limit where Planck's constant tends to zero, and usefully accurate for all values between 0 and the physical value (1 in atomic units). We also show that the Planck-constant-dependent symmetric ground-state density can be restored by spherical averaging of the broken-symmetry density.
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BibTeX
@misc{woods2026exactness,
title = {{Exactness of Symmetry-Broken Self-Interaction Correction in the Strongly-Correlated or Classical Limit: Harmonium as a Demonstration}},
author = {Cody Woods and Yunzhi Li and Wenqing Yao and Chen Li and John Perdew},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2607.22488},
eprint = {2607.22488},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2607.22488},
}
RIS
TY - UNPB
TI - Exactness of Symmetry-Broken Self-Interaction Correction in the Strongly-Correlated or Classical Limit: Harmonium as a Demonstration
AU - Cody Woods
AU - Yunzhi Li
AU - Wenqing Yao
AU - Chen Li
AU - John Perdew
PY - 2026
DA - 2026/09/12
PB - arXiv
DO - 10.48550/arxiv.2607.22488
UR - https://arxiv.org/abs/2607.22488
AB - Strong electron correlation is an important challenge to both wavefunction and density functional theory. It has been argued that the Perdew-Zunger 1981 self-interaction correction to any density functional approximation, after symmetry breaking, can correctly describe the ground-state energy in the strongly-correlated limit in which each electron is described by a highly-localized and non-overlapped one-electron spin orbital. It has also been argued that the classical limit, in which Planck's constant tends to zero, is the strongly-correlated limit of quantum mechanics, where standard density functionals fail badly, as demonstrated by the exactly-solvable problem of harmonium (two Coulomb-interacting electrons bound by a spherically-symmetric harmonic-oscillator external potential). Here we combine these two ideas and demonstrate that, for harmonium, symmetry-broken self-interaction correction is exact in the limit where Planck's constant tends to zero, and usefully accurate for all values between 0 and the physical value (1 in atomic units). We also show that the Planck-constant-dependent symmetric ground-state density can be restored by spherical averaging of the broken-symmetry density.
ER -