Influence of the solid surface vibrations on the rate constants of surface reactions

Vayssilov, Georgi N.

doi:10.1016/0001-8686(93)80005-v

Cited by 5 publications

(4 citation statements)

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“…For example, simulated diffusion rates within zeolite channels , can be much too rapid if the zeolite cage is held rigid. Second, dynamic modeling of sorption kinetics is necessary because activation energies for interfacial processes may be strongly dependent on surface phonons of the adsorbent . Also, neutron diffraction and EXAFS provide averaged interatomic distances which are not modeled realistically if the simulated system is not dynamic.…”

Section: Introductionmentioning

confidence: 99%

“…Second, dynamic modeling of sorption kinetics is necessary because activation energies for interfacial processes may be strongly dependent on surface phonons of the adsorbent. 21 Also, neutron diffraction and EXAFS provide averaged interatomic distances which are not modeled realistically if the simulated system is not dynamic. Finally, only a dynamic model for clays will allow the temperature dependence of mineral structures and spectra to be simulated.…”

Section: Introductionmentioning

confidence: 99%

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Molecular Dynamics Modeling of Clay Minerals. 1. Gibbsite, Kaolinite, Pyrophyllite, and Beidellite

et al. 1997

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A molecular dynamics model for clays and the oxide minerals is desirable for studying the kinetics and thermodynamics of adsorption processes. To this end, a valence force field for aluminous, dioctahedral clay minerals was developed. Novel aspects of this development include the bending potential for octahedral O−Al−O angles, which uses a quartic polynomial to create a double-well potential with minima at both 90° and 180°. Also, atomic point charges were derived from comparisons of ab initio molecular electrostatic potentials with X-ray diffraction-based deformation electron densities. Isothermal−isobaric molecular dynamics simulations of quartz, gibbsite, kaolinite, and pyrophyllite were used to refine the potential energy parameters. The resultant force field reproduced all the major structural parameters of these minerals to within 1% of their experimentally determined values. Transferability of the force field to simulations of adsorption onto clay mineral surfaces was tested through simulations of Na+, Ca2+, and hexadecyltrimethylammonium (HDTMA+) in the interlayers of beidellite clays. The new force field worked rather well with independently derived nonbonded parameters for all three adsorbates, as indicated by comparisons between experimental and molecular-dynamics-predicted d (001) layer spacings of the homoionic beidellites.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Molecular Dynamics Modeling of Clay Minerals. 1. Gibbsite, Kaolinite, Pyrophyllite, and Beidellite

et al. 1997

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“…The Brownian motion of atoms and atomic clusters on solid surfaces [1] is of interest for both the pure science and technology. It is relevant to surface coating [2], heterogeneous nucleation [3], catalysis [4], etc. [5].…”

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confidence: 99%

“…(8) is the first one. Hence, the potential is the same as that of a rigid dimer [9] and the activation energy for this case equals to 4 It is easy to recognize the activation energy of diffusion…”

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confidence: 99%

Resonant Diffusion on Solid Surfaces

Tsekov

1997

Surface Diffusion

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A new approach to Brownian motion of atomic clusters on solid surfaces is developed. The main topic discussed is the dependence of the diffusion coefficient on the fit between the surface static potential and the internal cluster configuration. It is shown this dependence is non-monotonous, which is the essence of the so-called resonant diffusion. Assuming quicker inner motion of the cluster than its translation, adiabatic separation of these variables is possible and a relatively simple expression for the diffusion coefficient is obtained. In this way, the role of cluster vibrations is accounted for, thus leading to a more complex resonance in the cluster surface mobility.The Brownian motion of atoms and atomic clusters on solid surfaces [1] is of interest for both the pure science and technology. It is relevant to surface coating [2], heterogeneous nucleation [3], catalysis [4], etc. [5]. Nowadays it is realized that the diffusion coefficient of homologies in solids exhibit non-monotone dependence on the molecular size. This phenomenon, called resonant diffusion, has been quantitatively described [6]. The problem here is, if there are resonant effects at the Brownian motion of atomic clusters on solid surfaces. Indeed, similar behavior was experimentally observed for diffusion of Re dimers on tungsten [1], Rh clusters on rhenium [7], etc. Despite the existing theoretical explanations [8,9], a proper adoption of modern methods for treatment of Brownian motion in modulated structures [10][11][12][13][14][15][16] to this important specific problem is required. The basic goal of this paper is to demonstrate a theoretical procedure for description of the resonant diffusion on solid surfaces.The main tool employed here is a formula derived by Festa and d'Agliano [17] providing possibility to calculate the diffusion coefficient D of a particle moving into a periodic potentialwhere U is the periodic potential with a period a and 1 / kT   is the reciprocal thermal energy. Strictly speaking, this formula is valid for the overdamped limit only. However, since we are interested in the large time behavior of the Brownian particle, this condition is always fulfilled. The first problem in the application of Eq. (1) is to determine the friction coefficient B . In the frames of the classical statistical mechanics it is possible to obtain a relation between the static potential on the solid surface U and the friction coefficient [13,15]

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Theoretical models for description of the gas-solid surface vibrational interactions

Vayssilov

1995

Advances in Colloid and Interface Science

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Influence of the solid surface vibrations on the rate constants of surface reactions

Cited by 5 publications

References 72 publications

Molecular Dynamics Modeling of Clay Minerals. 1. Gibbsite, Kaolinite, Pyrophyllite, and Beidellite

Molecular Dynamics Modeling of Clay Minerals. 1. Gibbsite, Kaolinite, Pyrophyllite, and Beidellite

Resonant Diffusion on Solid Surfaces

Theoretical models for description of the gas-solid surface vibrational interactions

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