Surface states and electronic properties for small Cadmium Sulfide nanocluster

In this work total and partial density of states were calculated for small single wurtzite CdS nanoparticle, quantum dots, with diameter below 2 nm, performing DFT pseudopotentials calculations with generalized gradient approximation. The cluster was previously heated at different temperatures ranging from 100 to 600 K-, by means of Car-Parrinello ab-initio molecular dynamics, finding a stable phase after 340 K. Another stable phase is reached at higher temperature, more than 480 K, where surface migrations play an important role in the determination of final atomic configuration. Density of states was obtained for the structures heated at 100 K, 280 K 330 K, 340 K, 480 K and 570 K and substantial modifications were found after 340 K where the superficial effects cause some alterations of the intermediate electronic states around the band gap. From the partial density of states it has been clearly showed that the atoms on the surface have a main role on the formation of the intermediate states on the band gap. This effect is meaningful for small particles where the fraction of the surface atoms is greater than the fraction of the core atoms.Copyright © 2013 American Scientific Publishers.