  We analyze a model problem representing a multi-electronic molecule sitting
on a metal surface. Working with a reduced configuration interaction
Hamiltonian, we show that one can extract very accurate ground state
wavefunctions as compared with the numerical renormalization group theory (NRG)
-- even in the limit of weak metal-molecule coupling strength but strong
intramolecular electron-electron repulsion. Moreover, we extract what appear to
be meaningful excitation energies as well. Our findings should lay the
groundwork for future {\em ab initio} studies of charge transfer processes and
bond making/breaking processes on metal surfaces.
