DIAGRAMMATIC MANY-BODY PERTURBATION EXPANSION FOR ATOMS AND MOLECULES .9. ON THE USE OF DYNAMIC LOAD BALANCING ON A MULTIPROCESSOR COMPUTER

A formulation of the diagrammatic many-body perturbation theory suitable for effective implementation on multi-processor computers is described. This concurrent computation many-body perturbation theory (ccMBPT) exploits the additive separability of the correlation energy components resulting from the linked diagram expansion to devise algorithms suitable for a parallel processing environment. A dynamic load balancing technique is employed to exploit the parallel processing capabilities of computers such as the CRAY Y-MP. The performance of the technique is demonstrated in calculations of the most computationally demanding of the fourth order energy components, those involving triply excited intermediate states. Execution rates in excess of 2.28 x 10(9) floating point operations per second are observed on an eight-processor machine.