Effect of the electron-phonon coupling on the ground state of a $D^{-}$ center in a spherical quantum dot

The influence of the electron-phonon coupling on the properties of a negatively charged donor center ${(D}^{-})$ confined in a semiconductor spherical quantum dot embedded in a glass matrix has been studied by variational means within the strong-coupling (Pekar) approach. A considerable enhancement of the binding is found for the $D^{-}$ ground state, which results from the strong confinement of electrons and electron-phonon coupling. Numerical results are given for quantum dots made of CdSe nanocrystals of variable radii.