Double H atom adsorption on a cluster model of a graphite surface

Rougeau, N.; Teillet‐Billy, D.; Sidis, V.

doi:10.1016/j.cplett.2006.09.069

Cited by 82 publications

(133 citation statements)

References 21 publications

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“…As expected, and in agreement with many previous DFT GGA studies, the barrier between the gas phase and the chemisorbed state is about 200 meV. 16,19,[32][33][34][35] The chemisorption well is 800 meV with a H−C bond length of 1.13 Å and puckering of the top site carbon atom away from the surface by ∼ 0.4 Å. With PBE there is no physisorption state, which is again consistent with previous work and understandable given the lack of a long-range correlation term in GGA exchange-correlation functionals.…”

Section: Hydrogen At Graphenesupporting

confidence: 92%

“…Hornekaer et al 16 and Rougeau et al 33 determined that once a single H atom has chemisorbed the barrier for subsequent H atoms to chemisorb locally is much smaller. Considered in concert with our findings this therefore facilitates the low temperature hydrogenation of large regions of graphene.…”

Section: Discussionmentioning

confidence: 99%

“…This barrier -which includes vdW, ZPE effects, quantum tunneling and finite temperature effects -is approximately half the height of barriers typically predicted for H atom chemisorption at graphene using traditional DFT-GGA methods. 16,19,[32][33][34][35] Although the barrier is substantially reduced the physisorption well remains relatively unperturbed, being a similar depth and shifted towards the gas phase by just ∼ 0.1 Å.…”

Section: Hydrogen At Graphenementioning

confidence: 99%

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Cooperative Interplay of van der Waals Forces and Quantum Nuclear Effects on Adsorption: H at Graphene and at Coronene

et al. 2014

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The energetic barriers that atoms and molecules often experience when binding to surfaces are incredibly important to a myriad of chemical and physical processes. However these barriers are difficult to describe accurately with current computer simulation approaches. Two prominent contemporary challenges faced by simulation are the role of van der Waals forces and nuclear quantum effects. Here we examine the widely studied model systems of hydrogen

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Section: Hydrogen At Graphenesupporting

confidence: 92%

Section: Discussionmentioning

confidence: 99%

Section: Hydrogen At Graphenementioning

confidence: 99%

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Cooperative Interplay of van der Waals Forces and Quantum Nuclear Effects on Adsorption: H at Graphene and at Coronene

et al. 2014

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“…This phenomenon is called puckering, and it creates a barrier against chemisorption of 0.2 eV. Recent studies by Rougeau et al (2006) and Hornekaer et al (2006) have shown that once an H atom is chemisorbed on graphite, and therefore a C atom has puckered out of the plane, the next H atom can chemisorb in certain neighbouring sites (para site) without any barrier. Another study by Bachellerie et al (2007) shows that, once an H atom is chemisorbed in a para site, a second H atom can also chemisorb at the same site without barrier and form a molecule.…”

Section: Discussionmentioning

confidence: 99%

The role of carbon grains in the deuteration of H₂

Cazaux

Caselli

Cobut

et al. 2008

A&A

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Aims. The production of molecular hydrogen and its deuterated forms onto carbonaceous dust grains is investigated in detail. The goal of this study is to estimate the importance of the chemistry occuring on grain surfaces for the deuteration of H 2 . Furthermore, we aim to find a robust and general surface chemical model that can be used in different astrophysical environments. Methods. Surface processes are described for the cases of graphitic and amorphous-carbon grains, where laboratory work is available. Langmuir-Hinshelwood, as well as Eley-Rideal surface chemistries are included in the model and their relative contributions highlighted. Analytic expressions are derived for H 2 , HD, and D 2 formation efficiencies for both types of grains. Rate equations are tested against stochastic methods. Results. As expected, rate equations and stochastic methods diverge for grain sizes below a critical value a crit . For these sizes, D 2 formation decreases to favour HD formation. The formation efficiencies of H 2 and D 2 can be calculated by adding a correction factor to the rate equations methods (this factor is a simple exponential factor that becomes unity when a > a crit ). We find that, because of the presence of chemisorbed sites, which can store atoms to form molecules up to high grain temperatures, the formation efficiency of HD and D 2 is very high compared to models where only physisorption sites are taken into account. When considering a realistic distribution of dust grains, we find that the formation rates of H 2 and HD are enhanced by an order of magnitude if small grains are taken into account. The formation of D 2 , on the other hand, comes from the contribution of small (≤100 Å) and big (≥100 Å) grains, depending on the D/H ratio, the grain temperature, and the volume density. The processes described in this paper, which allow a strong enhancement of the deuterated forms of molecular hydrogen, could explain the high degree of deuterium fractionation observed in protostellar environments.

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“…Thus, hydrogen adsorption on graphite is considered a key step for the ISM chemistry and its quantification is fundamental for the development of astrophysical models of star evolution. [3][4][5] The energetics of hydrogen adsorption has been extensively studied, mostly at the Density Functional Theory (DFT) level with the periodic supercell approach [6][7][8][9][10] and more lately with some accurate wavefunction calculations on cluster models. [11][12][13][14] Many different aspects of hydrogen adsorption have been addressed, including adsorption and diffusion in the a) Electronic mail: matteo.bonfanti@unimi.it b) Electronic mail: rocco.martinazzo@unimi.it shallow physisorption well, 11 single and multiple adsorption in the chemisorption well, 9,15-17 carbon vacancy hydrogenation, 18 and binding to edges.…”

Section: Introductionmentioning

confidence: 99%

Quantum dynamics of hydrogen atoms on graphene. I. System-bath modeling

Bonfanti

Jackson

Hughes

et al. 2015

The Journal of Chemical Physics

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Ab initio molecular dynamics of hydrogen dissociation on metal surfaces using neural networks and novelty sampling J. Chem. Phys. 127, 154716 (2007) An accurate system-bath model to investigate the quantum dynamics of hydrogen atoms chemisorbed on graphene is presented. The system comprises a hydrogen atom and the carbon atom from graphene that forms the covalent bond, and it is described by a previously developed 4D potential energy surface based on density functional theory ab initio data. The bath describes the rest of the carbon lattice and is obtained from an empirical force field through inversion of a classical equilibrium correlation function describing the hydrogen motion. By construction, model building easily accommodates improvements coming from the use of higher level electronic structure theory for the system. Further, it is well suited to a determination of the system-environment coupling by means of ab initio molecular dynamics. This paper details the system-bath modeling and shows its application to the quantum dynamics of vibrational relaxation of a chemisorbed hydrogen atom, which is here investigated at T = 0 K with the help of the multi-configuration time-dependent Hartree method. Paper II deals with the sticking dynamics. C 2015 AIP Publishing LLC. [http://dx

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Double H atom adsorption on a cluster model of a graphite surface

Cited by 82 publications

References 21 publications

Cooperative Interplay of van der Waals Forces and Quantum Nuclear Effects on Adsorption: H at Graphene and at Coronene

Cooperative Interplay of van der Waals Forces and Quantum Nuclear Effects on Adsorption: H at Graphene and at Coronene

The role of carbon grains in the deuteration of H₂

Quantum dynamics of hydrogen atoms on graphene. I. System-bath modeling

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Double H atom adsorption on a cluster model of a graphite surface

Cited by 82 publications

References 21 publications

Cooperative Interplay of van der Waals Forces and Quantum Nuclear Effects on Adsorption: H at Graphene and at Coronene

Cooperative Interplay of van der Waals Forces and Quantum Nuclear Effects on Adsorption: H at Graphene and at Coronene

The role of carbon grains in the deuteration of H2

Quantum dynamics of hydrogen atoms on graphene. I. System-bath modeling

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Product

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The role of carbon grains in the deuteration of H₂