Strong electron correlations determine energetic stability and electronic properties of Er-doped Goldberg-type silicon quantum dots

Atomic and electronic structures of Goldberg-type silicon quantum dots and their endohedral erbium complexes were studied using ab initio and plane wave pseudopotential density functional and Møller-Plesset manybody perturbation theories. During atomic structure optimizations, the erbium ions occupy mass centers inside the central hollows of quantum dots of different symmetries. It was found that strong electron correlations within the Er 4f shell taken into account by empirical pseudopotential and post-Hartree-Fock perturbation approaches are responsible for strong binding of Er ions to quantum dots. We elucidate the effects of symmetry and discuss theoretical results in comparison to available experimental data.