Molecular orbital calculations silver

Hamilton s original formulation contained the assumption that the individual silver atom center is highly unstable, an assumption not supported by molecular orbital calculations. 

I will illustrate the application of two techniques to the study of problems involving latent-image silver. These techniques are molecular orbital calculations and ultraviolet photoemission spectroscopy (UPS). The calculations are used to model the processes of formation of silver particles through photolysis. The spectroscopic measurements are used to determine properties of the silver particle as a function of its size. 

Figure 10. Structures used for the molecular orbital calculations, (a) PPS fragment, (b) Silver bonded to the PPS fragment with a trigonal pyramidal sulfur banding configuration.

This interaction can be probed using molecular orbital calculations. The most likely bonding site on PPS is the sulfur atom due to the strong affinity of silver for sulfur. The sulfiv atom can... 

Figure 11. Comparison of the experimental valence band spectrum for 2.Sxl0l atoms/cm silver on PPS and the calculated discrete orbital energy levels deteimined from the molecular orbital calculation on the PPS fragment bonded to silver in the trigonal pyramidal and trigonal planar sulfur bonding configurations.

UHF molecular orbital calculations were used to model specific silver/polymer interactions and compare the calculated energy levels with the experimental photoemission spectra at silver coverages in the subatomic regime. The calculations were found to be a useful aid in inteiprefing Ihe valence band spectra for low silver coverages and to provide insights into the effects in the polymer core levels. 

The assignment that the emissions arise from a LMCT [E M4] excited state with mixing of a metal-centered d sjd p) state has been substantiated by ab initio and Fenske-Hall molecular orbital calculations performed for the silver(I) clusters. These results revealed that the HOMOs of the clusters are principally Ag—E bonding orbitals, while the LUMOs are metal-localized orbitals with predominantly 55 and 5p character. Furthermore, the calculated HOMO-LUMO energy gaps decrease in the order (13a) > (13b) > (13c), consistent with the observed trend for the emission energies of the complexes. 

The bond strengths of ammonia, carbon monoxide, ethene and water to the copper and silver dimers have been obtained firom molecular orbital calculations and the results compared with experiment . ... 

Chemical considerations suggest that metal-olefin back donation will be less important for silver(I) than for platinum(II), and Basch s ab initio calculations on [Ag(C2H4)]+ (75) have confirmed this view. These calculations suggest that most of the electronic rearrangement of the ethylene unit in this complex ion can be accounted for by the polarization effects induced by the positive charge on the silver atom. Indeed, the bonding metal-olefin molecular orbital has only 6.5% Ag 5s orbital character. This result agrees nicely with recent ESR studies on y-irradiated silver-olefin complexes which estimate a 5s spin density of 4.6% for this molecular orbital 92, 93). 

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