Many-body pseudopotential theory of excitons in InP and CdSe quantum dots

We present a pseudopotential approach to the calculation of the excitonic spectrum of semiconductor quantum dots. Starting from a many-body expansion of the exciton wave functions in terms of single-substitution Slater determinants constructed from pseudopotential single-particle wave functions, our method permits an accurate and detailed treatment of the intraconfiguration electron-hole Coulomb and exchange interactions, while correlation effects can be included in a controlled fashion by allowing interconfiguration coupling. We calculate the exciton fine structure of InP and CdSe nanocrystals in the strong-confinement regime. We find a different size dependence for the electron-hole exchange interaction than previously assumed (i.e., $R^{-2}$ instead of $R^{-3})$. Our calculated exciton fine structure is compared with recent experimental results obtained by size-selective optical spectroscopies.