Diffusion of Muonium and Hydrogen in Diamond

Herrero, Carlos P.; Ramı́rez, Rafael

doi:10.1103/physrevlett.99.205504

Cited by 31 publications

(36 citation statements)

References 33 publications

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“…A detailed analysis of vibrational frequencies of hydrocarbon molecules derived with the present DF-TB potential, including anharmonicities, can be found elsewhere [37,38]. We have employed earlier this TB Hamiltonian to describe hydrogen-carbon interactions in diamond [35,39] and graphene [25]. The TB energy consists of two parts, the first one is the sum of energies of occupied one-electron states, and the second one is given by a pairwise repulsive interatomic potential [33].…”

Section: Methodsmentioning

confidence: 99%

“…Such quantum effects cause an effective renormalization of the diffusion barrier, which is reduced with respect to the high-temperature value. This can be studied by a combination of transition-state theory with quantum path-integral simulations, as has been done for hydrogen on a graphene sheet [25] and in bulk semiconductors [39,43], but is out of the scope of the present work.…”

Section: A Atomic Hydrogenmentioning

confidence: 99%

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Diffusion of hydrogen in graphite: a molecular dynamics simulation

Herrero¹,

Ramı́rez²

2010

J. Phys. D: Appl. Phys.

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Diffusion of atomic and molecular hydrogen in the interstitial space between graphite sheets has been studied by molecular dynamics simulations. Interatomic interactions were modeled by a tight-binding potential fitted to density-functional calculations. Atomic hydrogen is found to be bounded to C atoms, and its diffusion consists in jumping from a C atom to a neighboring one, with an activation energy of about 0.4 eV. Molecular hydrogen is less attached to the host sheets and diffuses faster than isolated H. At temperatures lower than 500 K, H 2 diffuses with an activation energy of 89 meV, whereas at higher T its diffusion is enhanced by longer jumps of the molecule as well as by correlations between successive hops, yielding an effective activation energy of 190 meV.

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Section: Methodsmentioning

confidence: 99%

Section: A Atomic Hydrogenmentioning

confidence: 99%

Diffusion of hydrogen in graphite: a molecular dynamics simulation

Herrero¹,

Ramı́rez²

2010

J. Phys. D: Appl. Phys.

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“…In this case, jump rates of hydrogen and muonium were calculated by QTST, using interatomic potentials derived from a tightbinding model 223 . This technique allowed to analyze the effect of vibrational mode quantization on the effective free-energy barriers ∆F for impurity diffusion, which are renormalized with respect to the zero-temperature classical calculation.…”

Section: B Diffusionmentioning

confidence: 99%

Path-integral simulation of solids

Herrero

Ramı́rez

2014

J. Phys.: Condens. Matter

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The path-integral formulation of the statistical mechanics of quantum many-body systems is described, with the purpose of introducing practical techniques for the simulation of solids. Monte Carlo and molecular dynamics methods for distinguishable quantum particles are presented, with particular attention to the isothermal-isobaric ensemble. Applications of these computational techniques to different types of solids are reviewed, including noble-gas solids (helium and heavier elements), group-IV materials (diamond and elemental semiconductors), and molecular solids (with emphasis on hydrogen and ice). Structural, vibrational, and thermodynamic properties of these materials are discussed. Applications also include point defects in solids (structure and diffusion), as well as nuclear quantum effects in solid surfaces and adsorbates. Different phenomena are discussed, as solid-to-solid and orientational phase transitions, rates of quantum processes, classical-to-quantum crossover, and various finite-temperature anharmonic effects (thermal expansion, isotopic effects, electron-phonon interactions). Nuclear quantum effects are most remarkable in the presence of light atoms, so that especial emphasis is laid on solids containing hydrogen as a constituent element or as an impurity.

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“…Path-integral methods analogous to that employed in this work have been applied earlier to study nuclear quantum effects in pure and hydrogen-doped carbonbased materials, as diamond [40][41][42] and graphite. 43 Helium adsorption 44 and diffusion of H on graphene 25 have been also studied earlier by using this kind of techniques.…”

Section: Introductionmentioning

confidence: 99%

Quantum effects in graphene monolayers: Path-integral simulations

Herrero

Ramı́rez

2016

The Journal of Chemical Physics

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113

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Path-integral molecular dynamics (PIMD) simulations have been carried out to study the influence of quantum dynamics of carbon atoms on the properties of a single graphene layer. Finitetemperature properties were analyzed in the range from 12 to 2000 K, by using the LCBOPII effective potential. To assess the magnitude of quantum effects in structural and thermodynamic properties of graphene, classical molecular dynamics simulations have been also performed. Particular emphasis has been laid on the atomic vibrations along the out-of-plane direction. Even though quantum effects are present in these vibrational modes, we show that at any finite temperature classical-like motion dominates over quantum delocalization, provided that the system size is large enough. Vibrational modes display an appreciable anharmonicity, as derived from a comparison between kinetic and potential energy of the carbon atoms. Nuclear quantum effects are found to be appreciable in the interatomic distance and layer area at finite temperatures. The thermal expansion coefficient resulting from PIMD simulations vanishes in the zero-temperature limit, in agreement with the third law of thermodynamics.

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Diffusion of Muonium and Hydrogen in Diamond

Cited by 31 publications

References 33 publications

Diffusion of hydrogen in graphite: a molecular dynamics simulation

Diffusion of hydrogen in graphite: a molecular dynamics simulation

Path-integral simulation of solids

Quantum effects in graphene monolayers: Path-integral simulations

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