Ab-initio molecular dynamics calculations: a parallel implementation of the Car-Parrinello method

We present a parallel implementation of the Car-Parrinello method (1985) for first principles molecular dynamics simulations, in the Parallel Virtual Machine (PVM, version 3.3.4) environment on the CRAY-T3D computer. Parallelism is achieved at the Single Program Multiple Data (SPMD) level, dividing among processors the calculations on different columns of a large matrix, containing the electronic wavefunctions of a condensed matter system object of the simulation, written in a plane-wave basis. Fast Fourier Transforms (FFTs) of these electronic states are the heaviest computations in the program. Communications are avoided an most of the code, except where the columns must be orthogonalized among each other. Even if it is not possible to make parallel the whole code, we have reached a parallel implementation of the most time-consuming part. We get an excellent behaviour of this part, and a satisfactory global behaviour