A density-functional study of cluster reactivity .3. NH3 on a free Ga5As5+ cationic cluster

Ammonia chemisorption on a small and positively charged gallium arsenide cluster in the gas phase has been investigated using density-functional methods. The reactivity at various cluster sites are characterized in terms of binding energy and charge transfer from the adsorbate to the cluster with a strong correlation shown between the latter two: quantities. The calculations show a strong dependence of the reactivity of the cluster on its charge state. Ionizing the bare cluster to a cationic charge state enables multiple chemisorption of ammonia, which is much less favored by a neutral cluster and can be prohibited on a negatively charged cluster. (C) 1996 American Institute of Physics.