Ephraim Eliav

Abstract:

Excited, ionized, and electron attached states of 3-D parabolic quantum dots (often referred to as "artificial" atoms) are treated with the relativistic 4-component multi-reference Intermediate Hamiltonian Fock-space coupled cluster method. Collective excitations, spin-orbital splittings and quasi-degenerate structure of many open shell quantum dots are important, implying the need for accurate inclusion of dynamic and non-dynamic correlation effects along with first principles relativistic treatment of excitation spectra. The effects of correlation and relativity on structure and properties of n-electronic quantum dots (with 1<n<60) has shown by calculating them at the high and low electronic density regions as a function of the potential strength parameter. Electronic correlation plays an important role, especially for low values of confining potential, where it constitutes a few percent of the total energy. Relativistic effects are more pronounced, when large values of confining potential are used. The spin-orbit effects are more dominant than scalar relativistic effects. Unlike in real atoms, in quantum dots relativistic effects are not affected by the system’s size, but only by the confining potential strength. In contrast to the case of the 2-D confining potential, where the magic numbers representing a “closed shell” structure are 2, 6, 12, 20, etc., in the 3-D potential case, one can clearly identify the shell structure 1s, 2p, 3d, 2s, 4f, 3p, 5g, etc., which is similar to the shell structure of the periodic table. Recently few-electrons quantum dots, confined by 3-dimensional isotropic harmonic potentials, with impurities that mimic finite-size atomic nuclei, have been also studied. The relative weight of the correlation correction is significant for these systems, in particular for small systems with weak confining potentials and low impurity charges Z, where it constitutes up to 17% of the total energy. Strong nonadditivity is observed for some low values of Z and ù, where correlation increases with Z and ù, opposite to the effect of each of these potentials separately. A suggestion is made to investigate quantum dots with impurities off the dot centre.