  We present a new cubic scaling algorithm for the calculation of the RPA
correlation energy. Our scheme splits up the dependence between the occupied
and virtual orbitals in $\chi^0$ by use of Cauchy's integral formula. This
introduces an additional integral to be carried out, for which we provide a
geometrically convergent quadrature rule. Our scheme also uses the newly
developed Interpolative Separable Density Fitting algorithm to further reduce
the computational cost in a way analogous to that of the Resolution of Identity
method.
