Theory of Adsorption and Desorption of H 2 /si(001) Typeset Using Revt E X
نویسنده
چکیده
While the small sticking coefficient for molecular hydrogen on the Si(001) surface apparently requires a large energy barrier of adsorption, no such barrier is observed in desorption experiments. We have calculated the potential-energy surface of an H 2 molecule in front of a Si(001) surface. If we relax the Si substrate, we find an optimum desorption path with a low (< ∼ 0.3 eV) ad-sorption energy barrier. While molecules impinging on the surface will mostly be reflected at the larger barrier of some frozen-substrate, molecules adsorbed on the surface can desorb along the low-barrier path.
منابع مشابه
The Reconstruction of Ni and Rh (001) Surfaces upon Carbon, Nitrogen, or Oxygen Adsorption Typeset Using Revt E X 1
Nickel and Rhodium (001) surfaces display a similar—as from STM images— clock reconstruction when half a monolayer of C/Ni, N/Ni or O/Rh is adsorbed; no reconstruction is observed instead for O/Ni. Adsorbate atoms sit at the center of the black squares of a chess-board, c(2 × 2), pattern and two different reconstructions are actually compatible with the observed STM images—showing a (2 × 2)p4g ...
متن کاملAdsorption of ethanol by using BN nanotube: a DFT study
Electrical sensitivity of a boron nitride nanotube (BNNT) was examined toward C2H5OH molecules by using density functional theory (DFT) calculations . It was founding that the adsorption energy(Ead) of ethanol on the pristine nanotubes is about -51.5 kJ / mol, but when the nanotube has been doped with Si and Al atoms , the adsorption and recovery time ch...
متن کاملAdsorption of 4 He on a Single C 60 Typeset Using Revt E X 1
The adsorption of 4He inside and outside a single fullerene C60 is studied. A physisorption potential is proposed. The energetics and structural features of C60HeN clusters are investigated. Particular attention is paid to the growth of the highly pronounced layered density profile. The evolution towards bulk liquid and surface thickness at the free interface are discussed. FILENAME: fuller.tex...
متن کاملQuantum Monte Carlo calculations of H2 dissociation on Si(001).
The dissociative adsorption of H2 on the Si(001) surface is theoretically investigated for several reaction pathways using quantum Monte Carlo methods. Our reaction energies and barriers are at large variance with those obtained with commonly used approximate exchange-correlation density functionals. Our results for adsorption support recent experimental findings, while, for desorption, the cal...
متن کاملEffect of the cluster size in modeling the H2 desorption and dissociative adsorption on Si„001..
Three different clusters, Si9H12 , Si15H16 , and Si21H20 , are used in density-functional theory calculations in conjunction with ab initio pseudopotentials to study how the energetics of H2 dissociative adsorption on and associative desorption from Si~001! depends on the cluster size. The results are compared to five-layer slab calculations using the same pseudopotentials and high quality plan...
متن کامل