  Recently, Hohenstein et al[1] introduced tensor hypercontraction density
fitting to decompose the rank-4 electron repulsion integral tensor as the
product of five rank-2 tensors. In this paper, we use this methodology to
construct an algorithm which calculates the approximate ground state energy in
O(L^4) operations. We test our method using several small molecules and show
that we quickly approach the CISD limit with a small number of auxiliary
functions.
