COMBINED HARTREE-FOCK AND DENSITY-FUNCTIONAL THEORY - A DISTRIBUTED-MEMORY PARALLEL IMPLEMENTATION

The parallelisation of an ab initio, Kohn-Sham density functional code for direct SCF energy and gradient evaluation calculations is described. The implementation of the parallel Hartree-Fock method uses the PRISM algorithm for the calculation of the two-electron integrals. A Kohn-Sham density functional code has been written by us and interfaced to GAUSSIAN 92. This code has also been parallelised and incorporated into a set of new 'links' for the GAUSSIAN 92 package. The work, although performed using one particular type of workstation 'cluster' (the Hewlett-Packard 9000-7xx series), has been based upon P.V.M. (Parallel Virtual Machine), a portable communications package which is already available for a large number of systems including many UNIX workstations. The methods described are, thus, applicable to any system which is supported by both the GAUSSIAN 92 program and the P.V.M. communications package with minimal changes required to the sequential code.