Theoretical study of small silicon clusters on a graphite layer

In a series of recent experiments, the HOMO-LUMO energy gaps of small Si cl usters deposited on a graphite substrate have been determined by Scanning T unneling Microscopy (STM). The values obtained were found to be substantial ly smaller than the energy gaps of corresponding passivated clusters. This work considers dimensional reduction as a possible mechanism for a sizeable energy gap narrowing by the example of the system Si-5. The impact of the graphite substrate on the deposited species is investigated in the framewor k of a pseudocluster model.