Parallelization of SCF calculations within Q-Chem

We have incorporated MPI based parallelism with dynamic fond balance into the Hartree-Fock and DFT modules of Q-Chem. A series of benchmark calculations consisting of both single point energy and gradient calculations were carried out to gauge the performance of the parallel modules. Calculations were 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. Scalability for the DFT and Hartree-Fock modules is demonstrated for up to 64 processors. (C) 2000 Elsevier Science B.V. All rights reserved.