Solid State Sciences, Volume 14, Issue 5, May 2012, Pages 567-573
E. Burresi, M. Celino
ENEA, Technical Unit for Faenza Material Technologies (UTTMATF), Faenza Research Laboratories, via Ravegnana, 186, Faenza 48018, Italy
ENEA C. R. Casaccia, via Anguillarese 301 00123 Rome, Italy
A single wurtzite phase of cadmium sulfide cluster is investigated by ab-initio molecular dynamics simulations at different temperatures, ranging from 100 K to 600 K. In this study we propose a possible procedure to characterize the CdS quantum dots system by means of molecular dynamics calculations using a standard Car-Parrinello scheme. In order to ensure the accuracy of the numerical approach, preliminary calculations to test pseudopotentials, cutoff and box size on both single atoms systems and Cd–Cd, S–S, Cd–S dimers have been performed. Calculated binding energies and bond lengths are obtained in good agreement with experimental data. Subsequently, an uncapped CdS cluster with size below 2 nm, 48 atoms of cadmium and 48 atoms of sulfur, in a wurtzite geometry was structurally optimized to minimize internal stresses. The CdS cluster has been carefully characterized structurally at several temperatures up to T = 600 K. At the temperature of 340 K atomic diffusion on the surface allows the onset of a new stable atomic configuration.