Influence of structural relaxation on the optical and electronic properties of embedded Ge nanocrystals

Structural relaxation is shown to be indispensable for the correct description of the electronic and optical properties of embedded group-IV nanocrystals. Ab initio calculations show that the energetic position of the localized gap states and, consequently, the optical spectra, are very sensitive with respect to the ionic relaxation. Comparison with the results obtained for the corresponding ideal structures allows to quantify the influence of the relaxation.