Pseudospectral double excitation configuration interaction

We present a pseudospectral formulation of the single reference, closed shell double excitation configuration interaction method using a generator state self-consistent electron pair approach. The method scales as O(n2N3), compared to the conventional scaling of O(n2N4+n3N3). In no case tested does the pseudospectral energy differ by more than 0.35 mhartree from the conventional result.