We make a detailed analysis of each possible spin-orbit coupling of zincblende narrow-gap cylindrical quantum dots built in a two-dimensional electron gas. These couplings are related to both bulk (Dresselhaus) and structure (Rashba) inversion asymmetries. We study the competition between electron-electron and spin-orbit interactions on electronic properties of 2-electron quantum dots.

We describe our progress in developing an ab initio computational scheme for the calculation of the dielectric response function of solids, with special emphasis here on Si and C clusters. All calculations are carried out employing a basis of localized atomic-like orbitals and include the evaluation of quasiparticle corrections. The self-energy operator is evaluated in the GW approximation, with a full frequency dependence for the dielectric matrix. The approach is convenient and computationally optimal for the calculation of optical properties of complex systems lacking full periodicity, such as surfaces and clusters. We present here the dielectric response functions of clusters with structures found after full equilibration via molecular dynamical simulations, and discuss the sensitivity of the optical properties to quasiparticle corrections.

We present binding energy calculations for Mg, Zn, and C substitutional shallow acceptors in GaN and AIN for both, wurtzite (WZ) and zincblende (ZB) crystal phases. The calculations are performed within the effective mass theory through the 6 × 6 Rashba-Sheka-Pikus and the Luttinger- Kohn matrix Hamiltonians for WZ and ZB bulk crystals, respectively. An analytic representation for the pseudopotential is used to introduce the nature of the impurity atom. The energy shift due to polaron effects is also considered in this approach. The estimated ionization energies are in good agreement with those reported experimentally and those reported theoretically employing other methods. We find that the binding energies for ZB GaN acceptors are shallower than the corresponding impurities in the WZ crystalline phase. The binding energy dependence upon the crystal field splitting in the WZ compounds is analyzed.