Using a new general-order determinant-based program, we construct compact configuration interaction and coupled-cluster wave functions by selecting the most important configurations, by weight, from a full configuration interaction or full coupled-cluster wave function. Our results show that for the symmetric dissociation of water, chemical accuracy can be achieved across the surface with similar to 2% of the full coupled-cluster expansion compared to similar to 10% of the full configuration interaction expansion. (c) 2005 Published by Elsevier B.V.