Parallelization of SCF calculations within Q-Chem

We have incorporated MPI based parallelism with dynamic fond balance into t he Hartree-Fock and DFT modules of Q-Chem. A series of benchmark calculatio ns consisting of both single point energy and gradient calculations were ca rried out to gauge the performance of the parallel modules. Calculations we re carried out on two different parallel computers, namely a shared memory Silicon Graphics Origin2000 and a distributed memory Gray T3E, to show the flexibility of the code and demonstrate the great utility of MPI. Scalabili ty for the DFT and Hartree-Fock modules is demonstrated for up to 64 proces sors. (C) 2000 Elsevier Science B.V. All rights reserved.