  An implementation of the coupled-cluster single- and double excitations
(CCSD) method on two-dimensional quantum dots is presented. Advantages and
limitations are studied through comparison with other high accuracy approaches
for two to eight confined electrons. The possibility to effectively use a very
large basis set is found to be an important advantage compared to full
configuration interaction implementations. For the two to eight electron ground
states, with a confinement strength close to what is used in experiments, the
error in the energy introduced by truncating triple excitations and beyond is
shown to be on the same level or less than the differences in energy given by
two different Quantum Monte Carlo methods. Convergence of the iterative
solution of the coupled cluster equations is, for some cases, found for
surprisingly weak confinement strengths even when starting from a
non-interacting basis. The limit where the missing triple and higher
excitations become relevant is investigated through comparison with full
Configuration Interaction results.
