Parallel implementation of a pseudo-spectral calculation of molecular energy levels: Application to the water dimer (H 2 O) 2 Original Research Article

Parallel implementation of an iterative determination of energy levels of large 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 Pseudo 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 distributed over all the processors. Application to the water dimer (H 2 O) 2 Vibration–Rotation spectrum shows a very good parallel efficiency up to 64 processors.