Adsorption Bond Energy Calculation

The energy of adsorption, Fads, is calculated by using the optimized geometries by  

The energies calculated by using different basis sets can vary widely. However, it needs to be stressed that the relative values are meaningful when comparing different sorbates/sorbents as long as the same basis set is used. 

Understanding 7r-Complexation Bond through Molecular Orbital Theory 

Using the NBO method, the results on electron occupancy (Oc) from population analysis of NAO are listed in Table 8.4 for the C atom in the adsorbate 

Orbital 5s 4dxy dxz 4dyz 44x2-y2 4dz2 E4rf S(55 -I- 4d) 

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Experimental heats of adsorption of H obtained on polyciystalline transition metal surfaces are shown in Figure 2a [63]. Calculated and experimental adsorption bond energies for H on the most close-packed surfaces of the transition metals are given in Figure 2b [64]. A diminution of the chemisorption bond strength is observed from center left to the right in each metal series (3d, 4d, and 5d). 

Initial Heats of Adsorption Calculated from Bond Energies and Dipole Moments ... 

Values of the heat of adsorption of hydrogen on various metals calculated by Eley (110) using Pauling s covalent bond energy formula, i.e.. 

The bond energy is calculated in two ways. The heat of adsorption , Eads, reflects the decomposition of the gas phase molecule into fragments followed by adsorption of these fragments onto the Pt cluster. The gas phase molecule was either H2 or CH4. 

Fassaert et al. (68) simulated H adsorption on a Cu surface by adding an additional electron per metal atom to the system. This approximation relies on the fact that atomic wave functions and energy levels are not too different for Ni and Cu and that their principal difference lies in the number of valence electrons. In the case of adsorption to Cu substrate, which has no unfilled d orbitals, the metal d orbitals do not participate in the bonding to H. All bonding takes place using the metal 4s orbitals. The calculated covalent bond energy is comparable on the Ni and Cu substrate models, so that from the results a distinction between the catalytic properties of the two metals cannot be made. 

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