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| 2. |
- Hellman, Anders, 1974, et al.
(författare)
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Hydrogen-Induced Reconstruction of Cu(100): Two-Dimensional and One-Dimensional Structures of Surface Hydride
- 2014
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Ingår i: Journal of Physical Chemistry C. - Washington : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 118:29, s. 15773-15778
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Tidskriftsartikel (refereegranskat)abstract
- Adsorption of atomic hydrogen has a remarkable influence on the structure and morphology of the Cu(I00) surface. We have examined two specific situations; the well-known reconstructed p(2 x 2)-H surface and a one-dimensional (6 X 1)-H surface resembling the stripe reconstruction observed in an electrochemical environment. High resolution electron energy loss spectroscopy and density functional calculations show that the H atoms occupy only surface sites and that H bonding in induced 3-fold Cu surface hollow sites is a structural key element. The calculations support a transient scenario in which H absorption in subsurface sites is a critical intermediate step in the reconstruction of the Cu surface. We find clear evidence in terms of characteristic properties, like the H-Cu bond lengths and the dipole excited vibrational mode spectra, that these structures consist of two-dimensional and one-dimensional structures of surface hydride.
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| 3. |
- Lee, Kyuho, et al.
(författare)
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Benchmarking van der Waals density functionals with experimental data: potential-energy curves for H2 molecules on Cu(111), (100) and (110) surfaces
- 2012
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Ingår i: Journal of Physics: Condensed Matter. - : IOP Publishing. - 0953-8984 .- 1361-648X. ; 24:42
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Tidskriftsartikel (refereegranskat)abstract
- Detailed physisorption data from experiment for the H2 molecule on low-index Cu surfaces challenge theory. Recently, density functional theory (DFT) has been developed to account for nonlocal correlation effects, including van der Waals (dispersion) forces. We show that the functional vdW-DF2 gives a potential-energy curve, potential-well energy levels and difference in lateral corrugation promisingly close to the results obtained by resonant elastic backscattering–diffraction experiments. The backscattering barrier is sensitive to the choice of exchange functional approximation. Further, the DFT-D3 and TS-vdW corrections to traditional DFT formulations are also benchmarked, and deviations are analyzed.
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| 4. |
- Lee, Kuyho, et al.
(författare)
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Evaluation of a density functional with account of van der Waals forces using experimental data of H2 physisorption on Cu(111)
- 2011
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Ingår i: Physical Review B. - 1098-0121. ; 84, s. 193408-
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Tidskriftsartikel (refereegranskat)abstract
- Detailed experimental data for physisorption potential-energy curves of H2 on low-indexed faces of Cu challenge theory. Recently, density-functional theory has been developed to also account for nonlocal correlation effects, including van der Waals forces. We show that one functional, denoted vdW-DF2, gives a potential-energy curve promisingly close to the experiment-derived physisorption-energy curve. The comparison also gives indications for further improvements of the functionals.
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| 5. |
- Svensson, Krister, 1969-, et al.
(författare)
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Desorption of H-2, HD, and D-2 through Temporary Negative Ion Formation
- 2012
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Ingår i: Physical Review Letters. - Ridge, NY : APS. - 0031-9007 .- 1079-7114. ; 109:19
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Tidskriftsartikel (refereegranskat)abstract
- Physically adsorbed H-2, HD, and D-2 desorbs via the low-energy (2)Sigma(+)(u) electron scattering resonance with characteristic electron energy dependent cross sections as we show by desorption and electron energy-loss measurements. Only H-2 and HD desorb, for energetic reasons, via excitation of the j = 0 -> 2 rotational mode and its subsequent decay into free translational motion, while all three isotopes desorb by direct transitions to unbound continuum states, with a probability close to unity and an unexpectedly weak mass dependence similar to m(-1/2).
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