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Surface magnetism of Rh(001) from LDA+U calculations

Materials Science · Submitted 6 Mar 2006 · 34 references

Pith's verdict: First realistic ab initio calculation to find Rh(001) surface magnetism, but the result is contingent on the SIC double-counting choice and an uncertain Ueff, so the claim that it resolves the experiment-theory gap is not supported.

T0 · AI review

How this review was made: An AI referee (deepseek-v4-flash) read the paper on August 28, 2026 and answered a fixed list of questions about it. T0 is the starting level every paper gets. The levels describe how deeply Pith has checked the paper, never the authors.

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  3. T2 Compute The paper's code or calculations re-run with the same results.
  4. T3 Formal statement The claims written out in a formal math language a computer can read.
  5. T4 Proof Those claims proved, and the proof checked by computer.

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arXiv IDcond-mat/0603127 (version 1)
Pith IDE542MP7Z, Pith's permanent record of this paper and its review
CitationM. Altarelli, N. Binggeli, N. Stojic. "Surface magnetism of Rh(001) from LDA+U calculations." arXiv:cond-mat/0603127 (2006). https://pith.science/paper/E542MP7Z
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Referee report
The paper

The paper claims

GGA+U calculations yield a ferromagnetic Rh(001) surface for Ueff of at least 1.2 eV, with the surface moment reaching 1.24 mu_B at Ueff = 2.5 eV.

The reading

Rhodium metal is not magnetic in its bulk form, but some experiments report a weak magnetic moment on its (001) surface, and older density functional theory (DFT) calculations could not reproduce this. This paper applies DFT with an extra on-site Coulomb repulsion term, known as LDA+U, to a slab of rhodium. The extra term penalizes two electrons sitting in the same 4d orbital. The authors scan the strength of this repulsion, called Ueff, from zero to 2.5 eV. Below 1.2 eV the surface stays nonmagnetic; at 1.2 eV and above, a ferromagnetic solution appears and is lower in energy than the nonmagnetic one. The magnetic moment on the outermost atoms grows from 0.07 mu_B at 1.2 eV to 1.24 mu_B at 2.5 eV. The authors estimate Ueff for rhodium as about 2.8 eV using a simpler tight-binding method, which is inside the magnetic range. They also check that other 4d and 5d surfaces (Mo, Ru, W, Ir) remain nonmagnetic with the same scheme, so LDA+U does not trivially make every surface magnetic. The calculated moment at the physically estimated Ueff is considerably larger than the experimental estimate of 0.1 to 0.2 mu_B, and the authors note that temperature effects and the uncertainty in Ueff prevent a quantitative comparison. The core conclusion is that the missing ingredient in older calculations may be the on-site Coulomb repulsion, not some other mechanism.
Extended reading notes

Core claim

The paper's central claim is that 'the application of the GGA plus on-site Coulomb interaction U method predicts surface magnetism, thus offering a solution to the long-standing discrepancy between experiment and theory.' More specifically, the ferromagnetic solution becomes stable for Ueff >= 1.2 eV, with m5 = 1.24 mu_B at Ueff = 2.5 eV, and the authors conclude that corrected non-local exchange-correlation is the key ingredient for an accurate DFT description of this surface.

Load-bearing premise

The load-bearing assumption is that the effective on-site Coulomb parameter Ueff for the Rh(001) surface is at least about 1.2 eV, and that the bulk-derived estimate Ueff ~ 2.8 eV (U = 3.4 eV, J = 0.6 eV from TB-LMTO) transfers to the surface. The authors state that calculated U and J values have error bars of about 1 eV, so a surface Ueff below 1.2 eV is not excluded. If Ueff were below threshold, the LDA+U calculation would give a nonmagnetic ground state and the proposed explanation of the experimental discrepancy would fail. This assumption is separate from the execution of the DFT calculations themselves.

Original abstract

We report calculations indicating the presence of a surface magnetic moment for Rh(001), motivated by the detection of a finite moment by magnetic linear dichroism experiments. We show that, while the density functional with the local density or generalized gradient approximations (LDA and GGA) for exchange and correlation yields a non-magnetic ground state, the application of the GGA plus on-site Coulomb interaction U method predicts surface magnetism, thus offering a solution to the long-standing discrepancy between experiment and theory. The calculated moment on the outermost Rh atom increases with the strength of the effective on-site parameter Ueff=U-J, for Ueff>=1.2 eV, and is as large as 1.24 mu_B for Ueff=2.5 eV.

The compiled record

The paper's own sentences, arranged, kept beside the review and separate from it. Each label is drawn from a closed vocabulary; the number beside it is the probability the classifier gave that label. Numbers in the tables are the authors', checked by code. No sentence in this record was written by a model.

Compiled by classifier-1.13-20260917 via OpenRouter, question bank abstract-p1-20260923, 2026-09-23: 1 request, 3,135 input tokens, $0.0001 reported.

What the abstract itself states, as probabilities: claims first 0.04 · states limitation 0.21 · human participants 0.01 · controlled comparison 0.43 · randomized assignment 0.01 · states quantitative result 0.99 · compares with prior results 0.96 · mentions code or data availability 0.02.

The abstract, sentence by sentence

arXiv listing abstract v1. Results and the main claim are underlined; .

We report calculations indicating the presence of a surface magnetic moment for Rh(001), motivated by the detection of a finite moment by magnetic linear dichroism experiments. We show that, while the density functional with the local density or generalized gradient approximations (LDA and GGA) for exchange and correlation yields a non-magnetic ground state, the application of the GGA plus on-site Coulomb interaction U method predicts surface magnetism, thus offering a solution to the long-standing discrepancy between experiment and theory. The calculated moment on the outermost Rh atom increases with the strength of the effective on-site parameter Ueff=U-J, for Ueff>=1.2 eV, and is as large as 1.24 mu_B for Ueff=2.5 eV.

background contribution method result interpretation main claim

What the classifier reports for each sentence. The number is the probability it gave the label.
#sentencerolethe authors' own workstates the main conclusionstrength
s0 We report calculations indicating the presence of a surface magnetic moment for Rh(001), motivated by the detection of a finite moment by magnetic linear dichroism experiments. result 0.51 0.89 0.44 hedged possibility 0.98
s1 We show that, while the density functional with the local density or generalized gradient approximations (LDA and GGA) for exchange and correlation yields a non-magnetic ground state, the application of the GGA plus on-site Coulomb interaction U method predicts surface magnetism, thus offering a solution to the long-standing discrepancy between experiment and theory. result 0.51 0.90 0.80 asserted 1.00
s2 The calculated moment on the outermost Rh atom increases with the strength of the effective on-site parameter Ueff=U-J, for Ueff>=1.2 eV, and is as large as 1.24 mu_B for Ueff=2.5 eV. result 1.00 0.94 0.23 asserted 1.00

What kind of paper the classifier reports this is: simulation study 0.99 · evidence from simulation or computation 1.00.

What was examined, and what was not

sources read
  • arXiv listing abstract v1
not examined
  • full text
  • figures and tables
  • references and citing sentences
  • relations to other papers
levels run
  • P abstract
not run
  • S sections
  • T body sentences
  • C citations
  • R cross-paper relations

Every quoted sentence on this record is the authors'. Every label is from Pith's closed vocabulary, with the probability shown beside it. Every number in the measurements table is the authors', checked by code. Record as JSON

Figures
Figure 1. FIG. 1: (Color online) Distribution of magnetic moments per
Figure 2. FIG. 2: Spin density difference map (in e/

Figures reproduced from arXiv:cond-mat/0603127 by the authors.

References

Discussion

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