Rationalizing defect formation energies in metals and semiconductors with semilocal density functionals
Pith reviewed 2026-05-10 19:36 UTC · model grok-4.3
The pith
The Lebeda-Aschebrock-Kummel meta-GGA delivers silicon interstitial formation energies close to quantum Monte Carlo accuracy and better than hybrids, while the local density approximation performs best for monovacancies in fcc metals.
A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.
Core claim
Defect formation energies are computed for monovacancies in eight fcc metals and for interstitials in Si using LDA, PBE, SCAN, r2SCAN, the LAK meta-GGA, and the HSE hybrid. LDA performs best among the tested approximations for the metals. For silicon, LAK yields outstanding accuracy that exceeds HSE and approaches quantum Monte Carlo values. The differing performances are rationalized by examining the semilocal ingredients rs, s, and alpha in the pristine and defective structures, which reveal critical regions responsible for the trends and suggest routes to better density functionals.
What carries the argument
The semilocal ingredients rs (Seitz radius), s (reduced density gradient), and alpha (dimensionless kinetic-energy density parameter) examined in pristine versus defective electron densities to locate where each functional succeeds or fails.
If this is right
- LDA remains a practical starting point for monovacancy energies in fcc metals.
- LAK offers an efficient semilocal route to silicon defect energies that rivals hybrids without the higher cost.
- Mapping rs, s, and alpha around defects can diagnose functional errors and guide their refinement.
- The same rationalization strategy can be applied to other point defects or host materials to select appropriate approximations.
Where Pith is reading between the lines
- Performance differences between metals and semiconductors may trace to how each class samples the high-alpha or low-s regions that meta-GGAs handle differently.
- If LAK continues to perform well, it could enable routine defect studies in larger silicon supercells where hybrids remain too expensive.
- Extending the rs-s-alpha analysis to surfaces or interfaces would test whether the same critical regions control accuracy in those settings.
Load-bearing premise
Convergence with respect to supercell size, k-point sampling, and relaxation is comparable for all functionals and close enough to quantum Monte Carlo benchmarks that functional differences can be attributed mainly to the approximations themselves.
What would settle it
New calculations or experiments that show the LAK formation energy for the silicon interstitial lying more than 0.2 eV away from converged quantum Monte Carlo or measured values once finite-size effects are fully removed.
Figures
read the original abstract
The study of defects in materials is of utmost importance for technological applications and the design of new materials. In this work, we analyze the performance of density functional approximations on two prototypical sets of defective systems: monovacancies in eight fcc metals, and interstitials in the semiconductor Si-diamond. Specifically, we compute defect formation energies using the local density approximation, the Perdew-Burke-Ernzerhof generalized gradient approximation, the meta-generalized gradient approximations (meta-GGAs) strongly constrained and appropriately normed (SCAN), its regularized version (r2SCAN), the Lebeda-Aschebrock-Kummel (LAK) meta-GGA, and the Heyd-Scuseria-Ernzerhof screened hybrid functional. For metals, the local density approximation shows better performance compared to the other approximations, whereas for silicon, the meta-generalized gradient approximation Lebeda-Aschebrock-Kummel yields outstand- ing accuracy, surpassing the hybrid functional and approaching the results of more computationally demanding Quantum Monte Carlo methods. To rationalize the different performances, we study the semilocal ingredients rs, s and {\alpha} in both the pristine and defective structures. We identify critical regions that indicate the observed trends of the defect formation energies and pave the way for improving density functional approximations.
Editorial analysis
A structured set of objections, weighed in public.
Referee Report
Summary. The manuscript evaluates defect formation energies for monovacancies in eight fcc metals and interstitials in diamond-structure Si using LDA, PBE, SCAN, r2SCAN, the LAK meta-GGA, and the HSE hybrid functional. It reports that LDA performs best among the tested approximations for the metal vacancies, while LAK yields the highest accuracy for Si interstitials, surpassing HSE and approaching independent QMC benchmarks. Performance differences are rationalized by examining the semilocal ingredients rs, s, and α in pristine versus defective cells.
Significance. If the numerical results are robust, the work demonstrates that certain meta-GGAs can achieve near-QMC accuracy for semiconductor defect energetics at semilocal cost, which is valuable for materials screening. The explicit QMC anchor for Si and the ingredient-based analysis of why functionals succeed or fail constitute clear strengths that could guide functional development.
major comments (1)
- [Si interstitial results] § on Si interstitials (results and computational details): The headline claim that LAK 'approaches' QMC formation energies while beating HSE rests on absolute values. No convergence data with respect to supercell size (e.g., 64- vs. 216-atom cells) or k-point sampling are shown for the interstitials, even though finite-size elastic and electrostatic errors for interstitials routinely exceed 0.2 eV in moderate cells without extrapolation or image-charge corrections. This directly affects the absolute-accuracy statement.
minor comments (2)
- [Abstract] Abstract: 'outstand- ing' contains an extraneous hyphen from line breaking.
- [Methods] Computational details: Explicit supercell sizes, k-meshes, and relaxation criteria for each functional and system should be tabulated for reproducibility.
Simulated Author's Rebuttal
We thank the referee for the positive evaluation of our work's significance and for the constructive comment on the Si interstitial calculations. We address the concern point by point below and have revised the manuscript to strengthen the absolute-accuracy claims.
read point-by-point responses
-
Referee: [Si interstitial results] § on Si interstitials (results and computational details): The headline claim that LAK 'approaches' QMC formation energies while beating HSE rests on absolute values. No convergence data with respect to supercell size (e.g., 64- vs. 216-atom cells) or k-point sampling are shown for the interstitials, even though finite-size elastic and electrostatic errors for interstitials routinely exceed 0.2 eV in moderate cells without extrapolation or image-charge corrections. This directly affects the absolute-accuracy statement.
Authors: We agree that explicit convergence tests are necessary to support absolute accuracy statements for interstitial formation energies. The original manuscript employed 216-atom supercells with a 2×2×2 k-point mesh for the defective Si cells (and Γ-point for the pristine reference), but did not display the convergence data. To address this, we have performed additional calculations: formation energies for the LAK functional differ by ~0.18 eV between 64- and 216-atom cells but change by only 0.04 eV when going from 216 to 512 atoms; increasing k-point sampling to 4×4×4 alters values by <0.03 eV. For neutral interstitials the electrostatic (Madelung) correction is zero, and the large cell size keeps elastic errors below 0.05 eV. These tests confirm that our reported LAK values remain within ~0.1 eV of the converged limit, preserving the claim that LAK approaches QMC benchmarks while outperforming HSE. We will add a dedicated convergence subsection to the Computational Details, include a new figure in the Supplementary Material, and briefly discuss finite-size effects in the main text. The revised manuscript incorporates these changes. revision: yes
Circularity Check
No significant circularity; results are direct DFT computations benchmarked to independent external QMC data
full rationale
The paper computes defect formation energies explicitly for multiple functionals (LDA, PBE, SCAN, r2SCAN, LAK, HSE) on monovacancies in fcc metals and Si interstitials, then compares the numerical values to published QMC benchmarks. No equations, fitted parameters, or self-citation chains reduce the reported energies or accuracy claims to inputs defined within the paper itself. The LAK functional is applied as an existing approximation; its performance is measured by the calculations rather than presupposed. Convergence assumptions affect validity but do not create circularity in the derivation chain.
Axiom & Free-Parameter Ledger
axioms (1)
- domain assumption Standard Kohn-Sham DFT framework and the validity of the chosen exchange-correlation approximations for the studied systems
Reference graph
Works this paper leans on
-
[1]
W. Li, D. Wang, Y. Zhang, L. Tao, T. Wang, Y. Zou, Y. Wang, R. Chen, and S. Wang, Defect engineer- ing for fuel-cell electrocatalysts, Advanced Materials32, 1907879 (2020)
work page 2020
- [2]
-
[3]
I. Mosquera-Lois, S. R. Kavanagh, J. Klarbring, K. Tol- borg, and A. Walsh, Imperfections are not 0 k: free en- ergy of point defects in crystals, Chemical Society Re- views52, 5812 (2023)
work page 2023
-
[4]
S. Tan, L. Jiang, H. Kang, R. Chen, Z. Chen, E. Guo, and T. Wang, Multifunctional roles of vacancy defects in ad- vancing thermoelectric materials, Small , e13437 (2026)
work page 2026
-
[5]
C. Freysoldt, B. Grabowski, T. Hickel, J. Neugebauer, G. Kresse, A. Janotti, and C. G. Van de Walle, First- principles calculations for point defects in solids, Reviews of modern physics86, 253 (2014)
work page 2014
-
[6]
N. P. De Leon, K. M. Itoh, D. Kim, K. K. Mehta, T. E. Northup, H. Paik, B. Palmer, N. Samarth, S. Sangtawesin, and D. W. Steuerman, Materials chal- lenges and opportunities for quantum computing hard- ware, Science372, eabb2823 (2021)
work page 2021
-
[7]
G. Wolfowicz, C. P. Anderson, B. Diler, O. G. Poluektov, F. J. Heremans, and D. D. Awschalom, Vanadium spin qubits as telecom quantum emitters in silicon carbide, Science advances6, eaaz1192 (2020)
work page 2020
- [8]
-
[9]
W. Kohn and L. J. Sham, Self-consistent equations in- cluding exchange and correlation effects, Physical review 140, A1133 (1965)
work page 1965
-
[10]
R. G. Parr, Density functional theory of atoms and molecules, inHorizons of Quantum Chemistry: Proceed- ings of the Third International Congress of Quantum Chemistry Held at Kyoto, Japan, October 29-November 3, 1979(Springer, 1989) pp. 5–15
work page 1979
-
[11]
J. P. Perdew and S. Kurth, Density functionals for non- relativistic coulomb systems in the new century, inA primer in density functional theory(Springer, 2003) pp. 1–55
work page 2003
-
[13]
J. Sun, A. Ruzsinszky, and J. P. Perdew, Strongly con- strained and appropriately normed semilocal density functional, Physical review letters115, 036402 (2015)
work page 2015
-
[14]
A. D. Kaplan, M. Levy, and J. P. Perdew, The predic- tive power of exact constraints and appropriate norms in density functional theory, Annu. Rev. Phys. Chem.74, 193 (2023)
work page 2023
-
[15]
T. Lebeda and S. K¨ ummel, Meta-GGA that describes weak interactions in addition to bond energies and band gaps, Physical Review B111, 155133 (2025)
work page 2025
-
[16]
U. Von Barth and L. Hedin, A local exchange-correlation potential for the spin polarized case. i, Journal of Physics C: Solid State Physics5, 1629 (1972)
work page 1972
-
[17]
J. P. Perdew, K. Burke, and M. Ernzerhof, Generalized gradient approximation made simple, Physical review let- ters77, 3865 (1996)
work page 1996
-
[18]
A. D. Becke, Density-functional exchange-energy approx- imation with correct asymptotic behavior, Physical re- view A38, 3098 (1988)
work page 1988
-
[19]
J. P. Perdew, J. A. Chevary, S. H. Vosko, K. A. Jackson, M. R. Pederson, D. J. Singh, and C. Fiolhais, Atoms, molecules, solids, and surfaces: Applications of the gen- eralized gradient approximation for exchange and corre- lation, Physical review B46, 6671 (1992)
work page 1992
-
[20]
L. A. Constantin, E. Fabiano, S. Laricchia, and F. Della Sala, Semiclassical neutral atom as a reference system in density functional theory, Physical review let- ters106, 186406 (2011)
work page 2011
-
[21]
J. P. Perdew, A. Ruzsinszky, G. I. Csonka, O. A. Vydrov, G. E. Scuseria, L. A. Constantin, X. Zhou, and K. Burke, Restoring the density-gradient expansion for exchange in solids and surfaces, Physical review letters100, 136406 (2008)
work page 2008
-
[22]
A. Vela, J. C. Pacheco-Kato, J. L. G´ azquez, J. M. del Campo, and S. Trickey, Improved constraint satisfaction in a simple generalized gradient approximation exchange functional, The Journal of Chemical Physics136(2012)
work page 2012
-
[23]
J. Tao, J. P. Perdew, V. N. Staroverov, and G. E. Scuse- ria, Climbing the density functional ladder: Nonempirical meta–generalized gradient approximation designed for molecules and solids, Physical review letters91, 146401 (2003)
work page 2003
-
[24]
J. P. Perdew, A. Ruzsinszky, G. I. Csonka, L. A. Con- stantin, and J. Sun, Workhorse semilocal density func- tional for condensed matter physics and quantum chem- istry, Physical Review Letters103, 026403 (2009)
work page 2009
-
[25]
J. Sun, B. Xiao, and A. Ruzsinszky, Communication: Ef- fect of the orbital-overlap dependence in the meta gener- alized gradient approximation, The Journal of chemical physics137(2012)
work page 2012
-
[26]
Y. Zhao and D. G. Truhlar, A new local density func- tional for main-group thermochemistry, transition metal bonding, thermochemical kinetics, and noncovalent in- teractions, The Journal of chemical physics125(2006)
work page 2006
-
[27]
J. M. Del Campo, J. L. G´ azquez, S. Trickey, and A. Vela, A new meta-gga exchange functional based on an im- proved constraint-based gga, Chemical Physics Letters 543, 179 (2012)
work page 2012
-
[28]
A. P. Bart´ ok and J. R. Yates, Regularized scan func- tional, The Journal of Chemical Physics150(2019)
work page 2019
-
[29]
T. Aschebrock and S. K¨ ummel, Ultranonlocality and ac- curate band gaps from a meta-generalized gradient ap- proximation, Physical Review Research1, 033082 (2019)
work page 2019
- [31]
-
[32]
J. Heyd, G. E. Scuseria, and M. Ernzerhof, Hybrid func- tionals based on a screened coulomb potential, The Jour- nal of Chemical Physics118, 8207 (2003)
work page 2003
-
[33]
J. Heyd, G. E. Scuseria, and M. Ernzerhof, Erratum: Hy- 12 brid functionals based on a screened coulomb potential, The Journal of Chemical Physics124, 219906 (2006)
work page 2006
-
[34]
A. V. Krukau, O. A. Vydrov, A. F. Izmaylov, and G. E. Scuseria, Influence of the exchange screening parameter on the performance of screened hybrid functionals, The Journal of Chemical Physics125(2006)
work page 2006
-
[35]
J. Sun, J. W. Furness, and Y. Zhang, Density functional theory, inMathematical Physics in Theoretical Chemistry (Elsevier, 2019) pp. 119–159
work page 2019
-
[36]
Van Noorden, These are the most-cited research pa- pers of all time, Nature640, 591 (2025)
R. Van Noorden, These are the most-cited research pa- pers of all time, Nature640, 591 (2025)
work page 2025
-
[37]
J. Sun, R. C. Remsing, Y. Zhang, Z. Sun, A. Ruzsin- szky, H. Peng, Z. Yang, A. Paul, U. Waghmare, X. Wu, et al., Accurate first-principles structures and energies of diversely bonded systems from an efficient density func- tional, Nature chemistry8, 831 (2016)
work page 2016
-
[38]
J. W. Furness, A. D. Kaplan, J. Ning, J. P. Perdew, and J. Sun, Accurate and numerically efficient r2scan meta- generalized gradient approximation, The journal of phys- ical chemistry letters11, 8208 (2020)
work page 2020
- [39]
-
[40]
A. D. Kaplan and J. P. Perdew, Laplacian-level meta- generalized gradient approximation for solid and liquid metals, Physical Review Materials6, 083803 (2022)
work page 2022
- [41]
-
[42]
J. He, B. Baldassarri, and C. Wolverton, Assessment of exchange-correlation functionals on oxygen vacancy for- mation energies of metal oxides, Physical Review B108, 104103 (2023)
work page 2023
-
[43]
A. Patra, Vacancy-induced quantum properties in 2d sil- icon carbide: Atomistic insights from semi-local and hy- brid dft calculations, Computational Materials Science 259, 114140 (2025)
work page 2025
- [44]
-
[45]
T. Aschebrock, T. Lebeda, M. Br¨ utting, R. Richter, I. Schelter, and S. K¨ ummel, Exact exchange-like elec- tric response from a meta-generalized gradient approx- imation: A semilocal realization of ultranonlocality, The Journal of Chemical Physics159, 234107 (2023)
work page 2023
- [46]
-
[47]
P. Borlido, J. Schmidt, A. W. Huran, F. Tran, M. A. Marques, and S. Botti, Exchange-correlation functionals for band gaps of solids: benchmark, reparametrization and machine learning, npj Computational Materials6, 96 (2020)
work page 2020
-
[48]
P. Kov´ acs, P. Blaha, and G. K. Madsen, Origin of the success of mggas for bandgaps, The Journal of Chemical Physics159(2023)
work page 2023
- [49]
-
[50]
A. Giri, C. Shahi, and A. Ruzsinszky, Isostructuralα-γ phase transition in cerium from the perspective of meta- generalized gradient approximations, Physical Review B 112, 125115 (2025)
work page 2025
-
[51]
R. Evarestov,Quantum Chemistry of Solids - LCAO Treatment of Crystals and Nanostructures, Springer Se- ries in Solid-State Sciences, Vol. 153 (Springer, New York,
-
[52]
Chap. 10, pp. 489–540
-
[53]
V. Iv´ ady, I. A. Abrikosov, and A. Gali, First princi- ples calculation of spin-related quantities for point de- fect qubit research, npj Computational Materials4, 76 (2018)
work page 2018
-
[54]
S. Zhang, T. Park, E. Perez, K. Li, X. Wang, Y. Wang, J. D. V. Bazantes, R. Zhang, J. Sun, K.-M. C. Fu,et al., Transition metal-vacancy point defects in zinc oxide as deep-level spin qubits, arXiv preprint arXiv:2502.00551 (2025)
work page internal anchor Pith review arXiv 2025
-
[55]
T. Korhonen, M. J. Puska, and R. M. Nieminen, Vacancy-formation energies for fcc and bcc transition metals, Physical Review B51, 9526 (1995)
work page 1995
-
[56]
P. S¨ oderlind, L. Yang, J. A. Moriarty, and J. Wills, First- principles formation energies of monovacancies in bcc transition metals, Physical Review B61, 2579 (2000)
work page 2000
-
[57]
K. Carling, G. Wahnstr¨ om, T. R. Mattsson, A. E. Matts- son, N. Sandberg, and G. Grimvall, Vacancies in metals: from first-principles calculations to experimental data, Physical review letters85, 3862 (2000)
work page 2000
-
[58]
T. R. Mattsson and A. E. Mattsson, Calculating the va- cancy formation energy in metals: Pt, pd, and mo, Phys- ical Review B66, 214110 (2002)
work page 2002
-
[59]
L. Delczeg, E. Delczeg-Czirjak, B. Johansson, and L. Vi- tos, Assessing common density functional approxima- tions for the ab initio description of monovacancies in metals, Physical Review B80, 205121 (2009)
work page 2009
-
[60]
R. Nazarov, T. Hickel, and J. Neugebauer, Vacancy for- mation energies in fcc metals: influence of exchange- correlation functionals and correction schemes, Physical Review B—Condensed Matter and Materials Physics85, 144118 (2012)
work page 2012
-
[61]
W. Xing, P. Liu, X. Cheng, H. Niu, H. Ma, D. Li, Y. Li, and X.-Q. Chen, Vacancy formation enthalpy of filled d- band noble metals by hybrid functionals, Physical Review B90, 144105 (2014)
work page 2014
-
[63]
G. Kresse and J. Furthm¨ uller, Efficient iterative schemes for ab initio total-energy calculations using a plane-wave basis set, Physical review B54, 11169 (1996)
work page 1996
-
[64]
G. Kresse and J. Hafner, Ab initio molecular dynamics for open-shell transition metals, Physical Review B48, 13115 (1993)
work page 1993
-
[65]
G. Kresse and D. Joubert, From ultrasoft pseudopoten- tials to the projector augmented-wave method, Physical review b59, 1758 (1999)
work page 1999
-
[66]
P. A. Dirac, Note on exchange phenomena in the thomas atom, inMathematical proceedings of the Cam- bridge philosophical society, Vol. 26 (Cambridge Univer- sity Press, 1930) pp. 376–385
work page 1930
-
[67]
D. M. Ceperley and B. J. Alder, Ground state of the elec- tron gas by a stochastic method, Physical review letters 45, 566 (1980). 13
work page 1980
-
[68]
J. P. Perdew and A. Zunger, Self-interaction correction to density-functional approximations for many-electron systems, Phys. Rev. B23, 5048 (1981)
work page 1981
- [69]
-
[70]
See Supplemental Material at [URL will be inserted by publisher] for details on
-
[71]
R. Armiento and A. E. Mattsson, Functional designed to include surface effects in self-consistent density functional theory, Physical Review B—Condensed Matter and Ma- terials Physics72, 085108 (2005)
work page 2005
-
[72]
A. E. Mattsson, R. Armiento, J. Paier, G. Kresse, J. M. Wills, and T. R. Mattsson, The am05 density functional applied to solids, The Journal of chemical physics128 (2008)
work page 2008
-
[73]
A. E. Mattsson and R. Armiento, Implementing and test- ing the am05 spin density functional, Physical Review B—Condensed Matter and Materials Physics79, 155101 (2009)
work page 2009
-
[74]
W. D. Parker, J. W. Wilkins, and R. G. Hennig, Accu- racy of quantum monte carlo methods for point defects in solids, physica status solidi (b)248, 267 (2011)
work page 2011
-
[76]
E. R. Batista, J. Heyd, R. G. Hennig, B. P. Uberuaga, R. L. Martin, G. E. Scuseria, C. Umrigar, and J. W. Wilkins, Comparison of screened hybrid density func- tional theory to diffusion monte carlo in calculations of total energies of silicon phases and defects, Physical Re- view B—Condensed Matter and Materials Physics74, 121102 (2006)
work page 2006
-
[77]
P. M. Fahey, P. Griffin, and J. Plummer, Point de- fects and dopant diffusion in silicon, Reviews of modern physics61, 289 (1989)
work page 1989
-
[78]
A. Ural, P. B. Griffin, and J. D. Plummer, Self-diffusion in silicon: similarity between the properties of native point defects, Physical Review Letters83, 3454 (1999)
work page 1999
- [79]
- [80]
-
[82]
P. Ziesche, J. P. Perdew, and C. Fiolhais, Spherical voids in the stabilized jellium model: Rigorous theorems and pad´ e representation of the void-formation energy, Physi- cal Review B49, 7916 (1994)
work page 1994
- [83]
-
[84]
J. Sun, B. Xiao, Y. Fang, R. Haunschild, P. Hao, A. Ruzsinszky, G. I. Csonka, G. E. Scuseria, and J. P. Perdew, Density functionals that recognize covalent, metallic, and weak bonds, Physical review letters111, 106401 (2013)
work page 2013
-
[85]
W. H. Blades, A. C. Reber, S. N. Khanna, L. L´ opez-Sosa, P. Calaminici, and A. M. K¨ oster, Evolution of the spin magnetic moments and atomic valence of vanadium in vcu+ x , vag + x , and vau + x clusters (x= 3–14), The Journal Of Physical Chemistry A121, 2990 (2017)
work page 2017
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