Parallel implementation of a pseudo-spectral calculation of molecular energy levels: Application to the water dimer (H2O)(2)

Parallel implementation of an iterative determination of energy levels of l arge molecular systems is presented. The basic step consists in acting the Hamiltonian operator H on a wavefunction u, and is achieved by means of a P seudo Spectral Split Hamiltonian scheme (Leforestier et al., J. Chem. Phys. 106 (1997) 8527). The potential term evaluation V.u, which corresponds by far to the most time consuming part in the sequential code, has been distri buted over all the processors. Application to the water dimer (H2O)(2) Vibr ation-Rotation spectrum shows a very good parallel efficiency up to 64 proc essors. (C) 2000 Elsevier Science B.V. All rights reserved.