REVIEW 3 major objections 6 minor 47 references
Time-dependent density-functional study of hydrogen adsorption and scattering on graphene surfaces
T0 review · 3 major / 6 minor · reviewed 2026-08-11 · deepseek-v4-flash
Pith's one-line read The exact spot where a hydrogen atom strikes a graphene-like sheet determines whether it adsorbs, scatters, or passes through—not just its energy or angle.
desk verdict Useful TDDFT incident-point scan, but the adsorption-likelihood claim is an extrapolation from a single edge-affected trajectory. read the letter →
The pith
A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.
The reading
What carries the argument
The central machinery is the time-dependent Kohn–Sham equation propagated on a real-space grid, with electron–ion interactions represented by norm-conserving pseudopotentials and exchange-correlation treated in the adiabatic local-density approximation. Ions move classically under Ehrenfest forces, so the model resolves energy flow between the projectile and the lattice. The target is coronene ($\mathrm{C}_{24}\mathrm{H}_{12}$), a seven-ring molecule chosen as a graphene surrogate because it fits the grid, and the diagnostic is the time-resolved kinetic energy of both the H atom and the carbon skeleton. A $4 \times 7$ grid of incident points with $0.3$ Å spacing isolates the impact-point variable while energy and angle are held fixed.
What would settle it
Run the same collision energies and angles on a larger graphene flake or a periodic supercell in the same TDDFT setup: if off-carbon impact points no longer show prolonged interaction and reduced energy transfer, or if no C–H bond forms at an interior ring, then the claimed impact-point control is an artifact of the coronene model.
Extended reading notes
Core claim
Using real-time TDDFT with Ehrenfest ion dynamics, the paper shows that the outcome of an H–graphene collision is governed by the impact point. For a projectile kinetic energy of $1.89$ eV at $27.4^\circ$ incidence, aiming at ring centers rather than directly at carbon atoms lengthens the interaction from roughly $5$ fs to about $20$ fs, reduces the energy transferred to the lattice (from up to $1.56$ eV down to $0.76$ eV), and shifts the final scattering angle from $3.4^\circ$ to $72.9^\circ$. At a more grazing $35^\circ$ incidence aimed at an off-carbon site, initial kinetic energies from $1.89$ to $3.50$ eV adsorb, $4.66$ to $6.35$ eV scatter after penetrating the barrier, and $9.14$ eV transmits through the sheet. The paper concludes that off-carbon impact points increase the likelihood of overcoming the potential barrier, rehybridizing a carbon from sp2 to sp3, and forming a covalent C–H bond; the one adsorption event shows a double-bounce trajectory before bonding at the coronene edge.
Load-bearing premise
The argument assumes that the seven-ring coronene molecule behaves like an infinite graphene sheet; the paper's own successful adsorption event occurs at the molecule's edge, where edge effects are acknowledged to play a role.
Editorial extensions
If this is right
- Incident points over ring centers, away from carbon atoms, should be the preferred targets for hydrogenation because they prolong the encounter and reduce energy transfer.
- At a fixed off-carbon impact point and a 35° incidence angle, initial kinetic energies between about 1.9 and 3.5 eV produce adsorption, while higher energies scatter or transmit, giving energy-selected beams a predictable outcome ladder.
- Scattering-angle distributions from H–graphene collisions should be broad and impact-site dependent, so measured angles can serve as a fingerprint of where the atom hit.
- Energy lost by the projectile is distributed between lattice vibrations and the electron density, so post-collision vibrational excitation of the sheet is a measurable consequence of the impact point.
Reading between the lines
- If the impact-point effect survives on an infinite sheet, a position-controlled H beam could hydrogenate graphene in patterns by aiming at ring centers—an application the paper does not propose.
- Because the successful adsorption event bonds at the coronene edge, a larger-flake or periodic calculation is the natural next test; the paper's own edge-effects caveat makes this the decisive open question.
- The double-bounce trajectory seen before bonding suggests transient C–H encounters may mediate chemisorption, a mechanism worth checking against full quantum-dynamics calculations of sticking.
- The quantitative energy window for adsorption (1.9–3.5 eV) is computed for coronene and could shift for graphene, so the thresholds are testable predictions rather than universal constants.
Editorial analysis
A structured set of objections, weighed in public.
Referee Report
Summary. The paper reports real-time time-dependent density-functional theory (TDDFT) simulations, with Ehrenfest ionic dynamics, of hydrogen atoms colliding with a coronene (C24H12) molecule used as a finite graphene model. A 28-trajectory scan varies the incident point on a 4×7 grid at fixed kinetic energy (1.89 eV) and incidence angle (27.4° from the surface normal), and a second set of 7 trajectories varies the kinetic energy at a single selected impact point and incidence angle (35°). The authors find that impact points farther from carbon atoms give longer interaction times and smaller kinetic-energy losses, and they interpret this as increasing the likelihood of C–H bond formation. One adsorption event is shown, occurring at the coronene edge, and the kinetic-energy scan yields adsorption (1.89–3.50 eV), scattering (4.66–6.35 eV), and transmission (9.14 eV) outcomes. The paper concludes that incident point, kinetic energy, and incidence angle are control variables for graphene hydrogenation.
Significance. If the central claim were fully demonstrated, the paper would usefully identify impact point as a control variable for hydrogenation, complementing prior work on kinetic energy and angle. The study has genuine strengths: it provides a systematic 28-point scan of impact positions within a consistent TDDFT framework, reports quantitative energy-transfer tables, gives scattering-angle distributions, and classifies adsorption/scattering/transmission outcomes without fitting a model to the data. The qualitative trends in interaction time, energy loss, and scattering angle are supported by the figures and tables. However, the central adsorption-likelihood claim is not directly shown by the data: all 28 incident-point trajectories scatter, and the only adsorption event changes two control variables simultaneously and occurs at the edge of the finite cluster. The finite-size and numerical-convergence issues are load-bearing for the extrapolation from coronene to graphene. These limitations are fixable with additional targeted simulations, so the work is a plausible candidate for publication after major revision.
major comments (3)
- [Section III.A, Figs. 2–5, Table I] The paper's central claim that impact points away from carbon atoms increase the likelihood of adsorption is inferred, not directly observed. All 28 trajectories in the incident-point scan scatter; the text states this explicitly ('the H atom failed to penetrate this barrier or form a bond with a C atom') and then uses longer interaction times and smaller kinetic-energy losses as proxies for higher adsorption probability. These proxies are suggestive but do not by themselves establish the causal claim made in the abstract and in Section III.A ('enhances the probability of C-H bond formation'). To substantiate the claim, the authors should either observe an adsorption event within an incident-point-only scan or provide a quantitative model connecting interaction time/energy loss to sticking probability.
- [Section III.B, Fig. 7, Table III] The single adsorption simulation does not isolate the incident-point variable. Relative to the 28-trajectory scan, it changes the incidence angle from 27.4° to 35° and uses an impact point x = -0.82 Å that was chosen after examining the earlier results. The stable bond then forms at the edge of the coronene molecule, and the text concedes that the bonding is affected by edge effects. The statement that a larger graphene system would likely bond in an interior benzene ring is an extrapolation, not a computed result. A run at the same angle as the incident-point scan, or a fixed-angle comparison across several impact points, is needed to separate the incident-point effect from the angle effect and from edge effects.
- [Section II (model and numerical parameters)] There is no convergence testing or error analysis for the numerical and model parameters. The results rest on a single grid spacing (0.25 Å), a single time step (δt = 1 as), a fixed simulation box, and the coronene cluster as a surrogate for graphene. The y1-row energy losses in Table I (0.76–1.00 eV) are not widely separated from the other rows (1.13–1.56 eV), and the adsorption event occurs at the cluster edge. Without a test with a smaller grid spacing, a longer simulation time, or a larger cluster/periodic slab, it remains unclear whether the qualitative trends and the adsorption threshold in Table III are robust to finite-size and discretization effects. This is load-bearing because the abstract's claim is about graphene surfaces, not solely about coronene edge sites.
minor comments (6)
- [Section III.A, after Fig. 6] The text states that the mean and median final kinetic energy of the H atoms are 0.62 eV and then says the H atom 'loses 1.42 eV of kinetic energy after scattering, as corroborated by the mean of the values in Table I.' The mean of Table I is 1.27 eV (1.89 eV initial minus 0.62 eV final), so the 1.42 eV value is internally inconsistent and should be corrected.
- [Table III] For the four adsorption simulations, the angle of reflection and the kinetic-energy loss are left as ellipses; reporting these values, or explicitly stating that they are not defined for bound trajectories, would make the table self-contained and would aid comparison with the scattering and transmission cases.
- [Section II, time propagation] The notation 'δt = 1 as' should specify whether the unit is attoseconds or atomic units of time, and it should be made consistent with the reported velocities (0.19 Å/fs) and the 80 fs simulation duration.
- [Table II caption] The caption contains the typo 'corenene'; it should read 'coronene.'
- [Fig. 6] The color legend (red, blue, yellow, green) may be difficult to distinguish in grayscale print; adding distinct symbols for the four incident-point columns would improve clarity.
- [References] Reference [35] is incomplete (missing a title, journal, volume, and year), and reference [44] appears to be a general textbook citation rather than a direct source for the specific real-space TDDFT propagation method; please verify and complete these citations.
Circularity Check
No significant circularity: the paper's outcomes are direct TDDFT simulation results, with no fitted parameters, and the sole self-citation is methodological and non-load-bearing.
full rationale
This is a computational simulation paper. The reported quantities—kinetic energy loss (Table I), vibrational energy transfer (Table II), scattering angles (Fig. 6), and adsorption/transmission outcomes (Table III)—are direct outputs of real-time TDDFT propagation on a coronene model, not quantities obtained by fitting equations to target observables. The initial kinetic energy (1.89 eV) and angle (27.4 degrees) are taken from an external study [18], and the adsorption run uses a newly chosen incident point and angle; its success is a computed outcome, not a parameter fitted to that outcome. The 1.89–3.50 eV adsorption range in Table III is a summary of simulation results, not a predicted quantity independent of those simulations. The only self-citation is reference [44], a textbook by one of the authors describing the real-space TDDFT method; the method's equations are fully stated in Section II, so the scientific conclusions do not rest on an unverified self-citation. The paper explicitly acknowledges that the single adsorption event occurs at the coronene edge and that extrapolation to an infinite graphene sheet is a qualitative expectation, which is a validity limitation, not circularity. No derived equation or prediction is equivalent to its inputs by construction.
Assumptions & free parameters
free parameters (6)
- Initial kinetic energy for the 28 incident-point simulations =
1.89 eV
- Incident angle for the 28 incident-point simulations =
27.4 degrees from z-axis
- Incident point for the adsorption simulations =
x = -0.82 Å
- Incident angle for the adsorption simulations =
35 degrees from z-axis
- Grid spacing =
0.25 Å
- Time step =
1 (atomic units implied)
assumptions (5)
- domain assumption The ALDA exchange-correlation functional is accurate for hydrogen-graphene scattering and energy transfer.
- domain assumption Classical (Ehrenfest) treatment of ion motion is sufficient for this problem.
- domain assumption Coronene is a representative model of graphene.
- standard math Norm-conserving Troullier-Martins pseudopotentials are transferable to this system.
- domain assumption The finite simulation grid does not introduce boundary effects that alter the trajectories.
Cite this review
Pith. "Pith review of Time-dependent density-functional study of hydrogen adsorption and scattering on graphene surfaces." pith.science (2026). https://pith.science/paper/LSFL36M6
@misc{pith2026241206939,
author = {Pith},
title = {Pith review of: Time-dependent density-functional study of hydrogen adsorption and scattering on graphene surfaces},
year = {2026},
howpublished = {\url{https://pith.science/paper/LSFL36M6}},
note = {Machine review of arXiv:2412.06939}
}
read the original abstract
Time-dependent density-functional theory simulations are performed to examine the effects of varying incident points and kinetic energies of hydrogen atom projectiles on a graphene-like structure. The simulations reveal that the incident point significantly influences the hydrogen atom's kinetic energy post-interaction, the vibrational dynamics of the graphene lattice, and the scattering angles. Incident points that do not directly collide with carbon atoms result in prolonged interaction times and reduced energy transfer, increasing the likelihood of overcoming the graphene's potential energy barrier and hydrogen atom adsorption. The study also explores the role of initial kinetic energy in determining adsorption, scattering, or transmission outcomes. These results emphasize the critical influence of initial parameters on the hydrogenation process and provide a foundation for future experimental validation and further exploration of hydrogen-graphene interactions.
Figures
Figures from the paper (4 more)
Reference graph
Works this paper leans on
-
[1]
D. G. Papageorgiou, I. A. Kinloch, and R. J. Young, Mechanical properties of graphene and graphene-based nanocomposites, Progress in Materials Science 90, 75 9 FIG. 7. Snapshots of a hydrogen projectile with an initial kinetic energy of 1.89 eV (velocity of 0.19 A/fs) being absorbed by a coronene molecule. The corresponding H atom kinetic energy (red soli...
work page 2017
-
[2]
C. Lee, X. Wei, J. W. Kysar, and J. Hone, Measure- ment of the elastic properties and intrinsic strength of monolayer graphene, Science 321, 385 (2008), https://www.science.org/doi/pdf/10.1126/science.1157996
- [3]
-
[4]
A. B. Kashuba, Conductivity of defectless graphene, Phys. Rev. B 78, 085415 (2008)
work page 2008
-
[5]
K. S. Novoselov, V. I. Falko, L. Colombo, P. R. Gellert, M. G. Schwab, and K. Kim, A roadmap for graphene, Nature 490, 192 (2012)
work page 2012
-
[6]
P. Avouris and F. Xia, Graphene applications in electron- ics and photonics, MRS Bulletin 37, 1225 (2012)
work page 2012
-
[7]
M. Sang, J. Shin, K. Kim, and K. J. Yu, Electronic and thermal properties of graphene and recent advances in graphene based electronics applications, Nanomaterials 9, 10.3390/nano9030374 (2019)
-
[8]
T. Mahmoudi, Y. Wang, and Y.-B. Hahn, Graphene and its derivatives for solar cells application, Nano Energy 47, 51 (2018)
work page 2018
Show all 47 references
-
[9]
S. Das, P. Sudhagar, Y. S. Kang, and W. Choi, Graphene synthesis and application for solar cells, Journal of Ma- terials Research 29, 299–319 (2014)
2014
-
[10]
Olabi, M
A. Olabi, M. A. Abdelkareem, T. Wilberforce, and E. T. Sayed, Application of graphene in energy storage device – a review, Renewable and Sustainable Energy Reviews 135, 110026 (2021)
2021
-
[11]
J. Zhu, D. Yang, Z. Yin, Q. Yan, and H. Zhang, Graphene and graphene-based materials for en- ergy storage applications, Small 10, 3480 (2014), https://onlinelibrary.wiley.com/doi/pdf/10.1002/smll.201303202
2014 doi
-
[12]
J. Liu, J. Tang, and J. J. Gooding, Strategies for chemical modification of graphene and applications of chemically modified graphene, J. Mater. Chem. 22, 12435 (2012)
2012
-
[13]
H. W. Ha, A. Choudhury, T. Kamal, D.-H. Kim, and S.-Y. Park, Effect of chemical modification of graphene on mechanical, electrical, and thermal properties of poly- imide/graphene nanocomposites, ACS Applied Materials & Interfaces 4, 4623 (2012)
2012
-
[14]
Kuila, S
T. Kuila, S. Bose, A. K. Mishra, P. Khanra, N. H. Kim, and J. H. Lee, Chemical functionalization of graphene and its applications, Progress in Materials Science 57, 1061 (2012)
2012
-
[15]
K. C. Kemp, H. Seema, M. Saleh, N. H. Le, K. Mahesh, 10 V. Chandra, and K. S. Kim, Environmental applications using graphene composites: water remediation and gas adsorption, Nanoscale 5, 3149 (2013)
2013
-
[16]
Li and L
X. Li and L. Zhi, Graphene hybridization for energy stor- age applications, Chem. Soc. Rev. 47, 3189 (2018)
2018
-
[17]
Balog, B
R. Balog, B. Jørgensen, L. Nilsson, M. Andersen, E. Rienks, M. Bianchi, M. Fanetti, E. Lægsgaard, A. Baraldi, S. Lizzit, Z. Sljivancanin, F. Besen- bacher, B. Hammer, T. G. Pedersen, P. Hofmann, and L. Hornekær, Bandgap opening in graphene induced by patterned hydrogen adsorpt...
2010
-
[18]
Jiang, M
H. Jiang, M. Kammler, F. Ding, Y. Dorenkamp, F. R. Manby, A. M. Wodtke, T. F. Miller, A. Kandratsenka, and O. B¨ unermann, Imag- ing covalent bond formation by h atom scat- tering from graphene, Science 364, 379 (2019), https://www.science.org/doi/pdf/10.1126/science.aaw6378
2019 doi
-
[19]
Hornekær, Stabilizing a c–h bond on graphene with sound, Science 364, 331 (2019), https://www.science.org/doi/pdf/10.1126/science.aax1980
L. Hornekær, Stabilizing a c–h bond on graphene with sound, Science 364, 331 (2019), https://www.science.org/doi/pdf/10.1126/science.aax1980
2019 doi
-
[20]
Bonfanti, S
M. Bonfanti, S. Achilli, and R. Martinazzo, Sticking of atomic hydrogen on graphene, Journal of Physics: Con- densed Matter 30, 283002 (2018)
2018
-
[21]
Casolo, O
S. Casolo, O. M. Løvvik, R. Martinazzo, and G. F. Tan- tardini, Understanding adsorption of hydrogen atoms on graphene, The Journal of Chemical Physics 130, 054704 (2009), https://pubs.aip.org/aip/jcp/article- pdf/doi/10.1063/1.3072333/15425402/054704 1 online.pdf
2009 doi
-
[22]
V. V. Ivanovskaya, A. Zobelli, D. Teillet-Billy, N. Rougeau, V. Sidis, and P. R. Briddon, Hydrogen ad- sorption on graphene: a first principles study, The Euro- pean Physical Journal B 76, 481 (2010)
2010
-
[23]
Jeloaica and V
L. Jeloaica and V. Sidis, Dft investigation of the adsorp- tion of atomic hydrogen on a cluster-model graphite sur- face, Chemical Physics Letters 300, 157 (1999)
1999
-
[24]
Sha and B
X. Sha and B. Jackson, First-principles study of the structural and energetic properties of h atoms on a graphite (0001) surface, Surface Science 496, 318 (2002)
2002
-
[25]
Ferro, F
Y. Ferro, F. Marinelli, and A. Allouche, Density functional theory investigation of h adsorption and h2 recombination on the basal plane and in the bulk of graphite: Connection between slab and cluster model, The Journal of Chemical Physics 116, 8124 (2002), https://pubs.aip.o...
2002
-
[26]
Tachikawa, T
H. Tachikawa, T. Iyama, and H. Kawabata, Density func- tional theory and direct molecular dynamics study of the hydrogen atom on a finite-sized graphene, Japanese Jour- nal of Applied Physics 49, 01AH06 (2010)
2010
-
[27]
C. P. Herrero and R. Ram ´ ırez, Vibrational properties and diffusion of hydrogen on graphene, Phys. Rev. B 79, 115429 (2009)
2009
-
[28]
Jain and B
V. Jain and B. Kandasubramanian, Functionalized graphene materials for hydrogen storage, Journal of Ma- terials Science 55, 1865 (2020)
2020
-
[29]
Tozzini and V
V. Tozzini and V. Pellegrini, Prospects for hydrogen stor- age in graphene, Phys. Chem. Chem. Phys.15, 80 (2013)
2013
-
[30]
H. G. Shiraz and O. Tavakoli, Investigation of graphene- based systems for hydrogen storage, Renewable and Sus- tainable Energy Reviews 74, 104 (2017)
2017
-
[31]
Gonz´ alez-Herrero, J
H. Gonz´ alez-Herrero, J. M. G´ omez-Rodr ´ ıguez, P. Mal- let, M. Moaied, J. J. Palacios, C. Salgado, M. M. Ugeda, J.-Y. Veuillen, F. Yndurain, and I. Bri- huega, Atomic-scale control of graphene magnetism by using hydrogen atoms, Science 352, 437 (2016), https://www.science....
2016 doi
-
[32]
D. W. Boukhvalov, M. I. Katsnelson, and A. I. Lichten- stein, Hydrogen on graphene: Electronic structure, total energy, structural distortions and magnetism from first- principles calculations, Phys. Rev. B 77, 035427 (2008)
2008
-
[33]
L. Shi, M. Schr¨ oder, H.-D. Meyer, D. Pelaez, A. M. Wodtke, K. Golibrzuch, A.-M. Sch¨ onemann, A. Kandrat- senka, and F. Gatti, Full quantum dynamics study for h atom scattering from graphene (2024), arXiv:2410.07246 [physics.chem-ph]
2024 arXiv
-
[34]
L. Shi, M. Schr¨ oder, H.-D. Meyer, D. Pel´ aez, A. M. Wodtke, K. Golibrzuch, A.-M. Sch¨ onemann, A. Kan- dratsenka, and F. Gatti, Quantum and classical molecular dynamics for h atom scattering from graphene, The Journal of Chemical Physics 159, 194102 (2023), https://pubs.aip...
2023 doi
-
[35]
A. Ito, A. Takayama, and H. Nakamura, Hydrogen ad- sorption of back side of graphene, (2007)
2007
-
[36]
Saito, A
S. Saito, A. M. Ito, and H. Nakamura, Molecular dy- namics simulation of the incident angle dependence of reactions between graphene and hydrogen atom, Plasma and Fusion Research 5, S2076 (2010)
2010
-
[37]
Nakamura and A
H. Nakamura and A. Ito, Molecular dynamics simulation of sputtering process of hydrogen and graphene sheets, Molecular Simulation 33, 121 (2007), https://doi.org/10.1080/08927020601078471
2007 doi
-
[38]
ITO and H
A. ITO and H. NAKAMURA, Molecular dynamics simu- lation of collisions between hydrogen and graphite, Jour- nal of Plasma Physics 72, 805–808 (2006)
2006
-
[39]
A. Ito, H. Nakamura, and A. Takayama, Molecu- lar dynamics simulation of the chemical interaction between hydrogen atom and graphene, Journal of the Physical Society of Japan 77, 114602 (2008), https://doi.org/10.1143/JPSJ.77.114602
2008 doi
-
[40]
Delfour, A
L. Delfour, A. Davydova, E. Despiau-Pujo, G. Cunge, D. B. Graves, and L. Magaud, Cleaning graphene: A first quantum/classical molecular dynam- ics approach, Journal of Applied Physics 119, 125309 (2016), https://pubs.aip.org/aip/jap/article- pdf/doi/10.1063/1.4945034/15181049/...
2016 doi
-
[41]
Bonfanti, B
M. Bonfanti, B. Jackson, K. H. Hughes, I. Burghardt, and R. Martinazzo, Quantum dy- namics of hydrogen atoms on graphene. ii. stick- ing, The Journal of Chemical Physics 143, 124704 (2015), https://pubs.aip.org/aip/jcp/article- pdf/doi/10.1063/1.4931117/14800085/124704 1 online.pdf
2015 doi
-
[42]
Nakamura, A
H. Nakamura, A. Takayama, and A. Ito, Molecular dynamics simulation of hydro- gen isotope injection into graphene, Contri- butions to Plasma Physics 48, 265 (2008), https://onlinelibrary.wiley.com/doi/pdf/10.1002/ctpp.200810046
2008 doi
-
[43]
Petucci, C
J. Petucci, C. LeBlond, M. Karimi, and G. Vi- dali, Diffusion, adsorption, and desorption of molecular hydrogen on graphene and in graphite, The Journal of Chemical Physics 139, 044706 (2013), https://pubs.aip.org/aip/jcp/article- pdf/doi/10.1063/1.4813919/14138673/044706 1 online.pdf
2013 doi
-
[44]
Varga and J
K. Varga and J. A. Driscoll, Monte carlo calculations, in Computational Nanoscience: Applications for Molecules, Clusters, and Solids(Cambridge University Press, 2011)
2011
-
[45]
Troullier and J
N. Troullier and J. L. Martins, Efficient pseudopoten- 11 tials for plane-wave calculations, Phys. Rev. B 43, 1993 (1991)
1991
-
[46]
J. P. Perdew and A. Zunger, Self-interaction correction to density-functional approximations for many-electron systems, Phys. Rev. B 23, 5048 (1981)
1981
-
[47]
T. J. Boerner, S. Deems, T. R. Furlani, S. L. Knuth, and J. Towns, Access: Advancing innovation: Nsf’s ad- vanced cyberinfrastructure coordination ecosystem: Ser- vices & support, in Practice and Experience in Advanced Research Computing 2023: Computing for the Common Good, PE...
2023
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