Porting and optimising a quantum-chemistry FCI algorithm on the Cray T3D

A Full Configuration Interaction algorithm has been optimised for a Cray T3D massively parallel computer. A preliminary version of the code showed good scalability, but also load unbalancing problems and synchronisation overheads. In this paper are described several ways to overcome these problems. A optimal solution has been found to eliminate the need of synchronisation points while load unbalancing appears to depend on the theoretical formulation of the problem. Also in this case some hints are suggested for future works.