Machine-learning semi-local exchange-correlation functionals for Kohn-Sham density functional theory of the Hubbard model

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Main Authors: Cronin, Eoghan, Tiwari, Rajarshi, Sanvito, Stefano
Format: Preprint
Published: 2025
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author Cronin, Eoghan
Tiwari, Rajarshi
Sanvito, Stefano
author_facet Cronin, Eoghan
Tiwari, Rajarshi
Sanvito, Stefano
contents The Hubbard model provides a test bed to investigate the complex behaviour arising from electron-electron interaction in strongly-correlated systems and naturally emerges as the foundation model for lattice density functional theory (DFT). Similarly to conventional DFT, lattice DFT computes the ground-state energy of a given Hubbard model, by minimising a universal energy functional of the on-site occupations. Here we use machine learning to construct a class of scalable `semi-local' exchange-correlation functionals with an arbitrary degree of non-locality for the one-dimensional spinfull Hubbard model. Then, by functional derivative we construct an associated Kohn-Sham potential, that is used to solve the associated Kohn-Sham equations. After having investigated how the accuracy of the semi-local approximation depends on the degree of non-locality, we use our Kohn-Sham scheme to compute the polarizability of linear chains, either homogeneous or disordered, approaching the thermodynamic limit. approaching the thermodynamic limit.
format Preprint
id arxiv_https___arxiv_org_abs_2501_16893
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Machine-learning semi-local exchange-correlation functionals for Kohn-Sham density functional theory of the Hubbard model
Cronin, Eoghan
Tiwari, Rajarshi
Sanvito, Stefano
Strongly Correlated Electrons
The Hubbard model provides a test bed to investigate the complex behaviour arising from electron-electron interaction in strongly-correlated systems and naturally emerges as the foundation model for lattice density functional theory (DFT). Similarly to conventional DFT, lattice DFT computes the ground-state energy of a given Hubbard model, by minimising a universal energy functional of the on-site occupations. Here we use machine learning to construct a class of scalable `semi-local' exchange-correlation functionals with an arbitrary degree of non-locality for the one-dimensional spinfull Hubbard model. Then, by functional derivative we construct an associated Kohn-Sham potential, that is used to solve the associated Kohn-Sham equations. After having investigated how the accuracy of the semi-local approximation depends on the degree of non-locality, we use our Kohn-Sham scheme to compute the polarizability of linear chains, either homogeneous or disordered, approaching the thermodynamic limit. approaching the thermodynamic limit.
title Machine-learning semi-local exchange-correlation functionals for Kohn-Sham density functional theory of the Hubbard model
topic Strongly Correlated Electrons
url https://arxiv.org/abs/2501.16893