  We have calculated the exchange, correlation, and total electronic energy of
a realistic InAs self-assembled quantum dot embedded in a GaAs matrix as a
function of the number of electrons in the dot. The many-body interactions have
been treated using the local spin density approximation (LSDA) to density
functional theory (DFT) and diffusion quantum Monte Carlo (DMC), so that we may
quantify the error introduced by LSDA. The comparison shows that the LSDA
errors are about 1-2 meV per electron for the system considered. These errors
are small enough to justify the use of LSDA calculations to test models of
self-assembled dots against current experimental measurements.
