  By expressing the electronic wavefunction in an explicitly-correlated
(Jastrow-factorised) form, a similarity-transformed effective Hamiltonian can
be derived. The effective Hamiltonian is non-Hermitian and contains three-body
interactions. The resulting ground-state eigenvalue problem can be solved
projectively using a stochastic configuration-interaction formalism. Our
approach permits use of highly flexible Jastrow functions, which we show to be
effective in achieving extremely high accuracy, even with small basis sets.
Results are presented for the total energies and ionisation potentials of the
first-row atoms, achieving accuracy within a mH of the basis-set limit, using
modest basis sets and computational effort.
