Confined quantum systems: dipole transition moment of two- and three-electron quantum dots, and of helium and lithium atoms in a harmonic oscillator potential

Abstract

The dipole transition moment between several low-lying singlet and doublet states of two- and three-electron quantum dots, and of helium and lithium atoms confined by an anisotropic harmonic oscillator potential, have been studied for different confinement strengths and shapes. The configuration interaction method has been used, employing a Cartesian anisotropic Gaussian basis set in the case of the two- and three-electron quantum dots. The basis set has been supplemented by a standard Cartesian Gaussian basis set in the case of the helium and lithium atoms. Except for the helium atom the dipole transition moments decrease strongly with increasing confinement strength ω. For some states of the lithium atom the transition moment varies strongly with the shape of the confining potential. For the helium atom the transition moments are considerably smaller as compared to the other three systems and rather invariant to a variation of the strength ω and of the shape of the confining potential . The described characteristic behaviour of the dipole transition moment for different systems and states is rationalized in terms of the size and shape of their electron density distribution.