  We apply the method of Monte Carlo configuration interaction (MCCI) to
calculate ground-state potential energy curves for a range of small molecules
and compare the results with full configuration interaction. We show that the
MCCI potential energy curve can be calculated to relatively good accuracy, as
quantified using the non-parallelity error, using only a very small fraction of
the FCI space. In most cases the potential curve is of better accuracy than its
constituent single-point energies. We finally test the MCCI program on systems
with basis sets beyond full configuration interaction: a lattice of fifty
hydrogen atoms and ethylene. The results for ethylene agree fairly well with
other computational work while for the lattice of fifty hydrogens we find that
the fraction of the full configuration interaction space we were able to
consider appears to be too small as, although some qualitative features are
reproduced, the potential curve is less accurate.
