Effect of the Gradient of the Spin-Polarization in Density Functional Approximations

Fuente: arXiv
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Main Authors: Maniar, Rohan, Perdew, John P.
Format: Preprint
Published: 2025
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author Maniar, Rohan
Perdew, John P.
author_facet Maniar, Rohan
Perdew, John P.
contents The construction of non-empirical density functional approximations is typically guided by the satisfaction of exact constraints. An important constraint is the recovery of the gradient expansion for slowly varying electron densities. In prior constructions of semilocal density functional approximations, the $\nabla ζ$-dependent terms in the gradient expansion of the correlation have been dropped, where $ζ$ is the relative spin polarization. We propose a scheme by which such terms can be reintroduced into already constructed functionals without significantly affecting other constraints and norms. We implement this scheme on the Strongly Constrained and Appropriately Normed (SCAN) functional to construct a $\nabla ζ$-corrected version of SCAN. The resulting functional is shown to provide improvements in transition-metal atoms and molecules without significantly affecting SCAN's accurate description of $sp$-systems. For the binding energy curve of the chromium dimer Cr$_2$, the SCAN underbinding is fully corected at large bond lengths and reduced at short bond lengths.
format Preprint
id arxiv_https___arxiv_org_abs_2512_08913
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Effect of the Gradient of the Spin-Polarization in Density Functional Approximations
Maniar, Rohan
Perdew, John P.
Chemical Physics
The construction of non-empirical density functional approximations is typically guided by the satisfaction of exact constraints. An important constraint is the recovery of the gradient expansion for slowly varying electron densities. In prior constructions of semilocal density functional approximations, the $\nabla ζ$-dependent terms in the gradient expansion of the correlation have been dropped, where $ζ$ is the relative spin polarization. We propose a scheme by which such terms can be reintroduced into already constructed functionals without significantly affecting other constraints and norms. We implement this scheme on the Strongly Constrained and Appropriately Normed (SCAN) functional to construct a $\nabla ζ$-corrected version of SCAN. The resulting functional is shown to provide improvements in transition-metal atoms and molecules without significantly affecting SCAN's accurate description of $sp$-systems. For the binding energy curve of the chromium dimer Cr$_2$, the SCAN underbinding is fully corected at large bond lengths and reduced at short bond lengths.
title Effect of the Gradient of the Spin-Polarization in Density Functional Approximations
topic Chemical Physics
url https://arxiv.org/abs/2512.08913