Modelling Molecules in Intense Laser Fields - Numerical Methods for an IBM-SP2 Parallel Computer Environment

Abstract

The behaviour, control and manipulation of molecules exposed to ultrashort (femtosecond) intense (>10**14 W/cm2) is of current interest to the new femtosecond technology including ultrafast electronic and electromagnetic technologies. The theoretical modelling and simulation of the interaction of molecules with the new ultashort and intense laser pulses available today requires large scale computations as one is dealing with nonlinear nonperturbative phenomena coupling two fundamental partial differential equations, pdf, s, the hyperbolic Maxwell equations of electromagnetism and the quantum equations of Schroedinger and Dirac for the molecules. Most of our work in this area involving nonperturbative solutions of these equations which are of interest to modem photochemistry and photophysics has been performed on IBM-SP2, s with 16 processors at CACPUS and up to a hundred processors at the Maui High Performance Computing Center.

Special high order numerical methods, based on split operator methods and large matrix Lanczos diagonaliztion preocedures have been developped to treat nonperturbatively such laser-molecule systems. We will describe in the present paper these new methods, their advantages over previous ones, their limitations and possible improvements compatible with new supercomputer technologies.