Two major contributions to the shift of the C-O stretch vibrational frequency between free CO and chemisorbed CO/C\*:(lOO) are identified. The overlap and consequent repulsion between the CO and metal orbit& leads to an increase in the frequency. The metal charge donation and dative bonding to CO 2-
Vibrations of CO on strained Cu(100) surfaces. A cluster model analysis
โ Scribed by Jordi Casanovas; Gianfranco Pacchioni
- Publisher
- Elsevier Science
- Year
- 1996
- Tongue
- English
- Weight
- 500 KB
- Volume
- 259
- Category
- Article
- ISSN
- 0009-2614
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โฆ Synopsis
The dependence of the vibrational stretching frequency, toe, of CO adsorbed on compressed or expanded Cu(lO0) layers has been studied theoretically by means of ab initio cluster model wavefunctions. It is found that even moderate changes in the surface distances result in measurable shifts in toe(CO) with an almost linear dependence of the to shift on the Cu-Cu distance. This is primarily due to a change in the back-donation from the surface to CO. It is also found that strain within the Cu layers is much more important than changes in the inter-layer spacing in determining the effect.
๐ SIMILAR VOLUMES
We have performed slab calculations on the periodic adsorption, with a coverage 0 = 0.5, of CO on the Cu( 100) surface. Using nonlocal corrections to the local density approximation (LDA), the calculated chemisorption energy is 0.7 eV, and the top site is slightly preferred over the hollow site. The
A density functional model cluster study of CO adsorbed on a MgO(001) surface has been carried out in order to accurately estimate bonding and vibrational parameters of the adsorption complex and to make a thorough analysis of the observables. Computed data for extended stoichiometric cluster models
XO~ scattered-wave calculations have been performed to compare the photon energy dependence of rhe valence level photoionization CIOSS sections of molecular CO and N2 and of Ni clusters simulatmg the adsorption of these molecules in the range of the shape resonances. Care has to be taken to avoid mu