An efficient parallel algorithm for the calculation of canonical MP2 energies

We present the parallel version of a previous serial algorithm for the efficient calculation of canonical MP2 energies (Pula.y. P.; Saebo, S.:, Wolinski, K. Chem Phys Lett 2001, 344, 543), It is based on the Saeho-Almlof direct-integral transformation. coupled with an efficient prescreening of the AO integrals. The parallel algorithm avoids synchronization delays by spawning a second set of slaves during the bin-sort prior to the second half-transformation, Results are presented for systems with up to 2000 basis functions. MP2 energies for molecule,, with 400-500 basis functions can be routinely calculated to microhartree accuracy on a small number of processors, (6-8) in a matter of minutes with modem PC-based parallel computers.