Large-scale correlated electronic structure calculations: The RI-MP2 method on parallel computers

The approximate 'resolution of the identity' second-order many-body perturbation theory method (RI-MP2) recently introduced by Feyereisen, Fitzgerald and Komornicki utilizes a combination of two-and three-center integrals to approximate the usual four-center two-electron repulsion integrals. Like the exact MP2, the overall cost of the RI-MP2 method scales with the fifth power of the number of basis functions, however the balance of the work shifts in such a way as to make the RI-MP2 method particularly well suited for implementation on massively parallel computers. We describe such an implementation and examine its parallel performance for several chemical systems. We are able to accurately reproduce the exact MP2 binding energy of K⁺ to 12-crown-4 ether in roughly 5% of the time.