The binding energy of a negatively charged hydrogenic impurity with on- and off-center position in a spherical Gaussian quantum dot was calculated with the configuration interaction method. Our calculations show that Eb is always positive for on-center impurities with a maximum near to the radius for one-electron stability of the potential well Rc. For off-center positions the binding energy can assume negative values within a range of the quantum dot radius, thus indicating the instability of the system.
@article{arxiv.0904.4700,
title = {Binding energy of an off-center shallow donor D- in a spherical quantum dot},
author = {Sergio S. Gomez and Rodolfo H. Romero},
journal= {arXiv preprint arXiv:0904.4700},
year = {2015}
}