This grant is being made jointly by the Theoretical and Computational Chemistry Program in the Chemistry Division and the New Technologies Program in the Division for Advanced Scientific Computing. The purpose of the work is to develop new methods for computing the outcomes of collisions between molecules, suitable for modern supercomputer architectures. The work involves interdisciplinary collaboration between Professor Wyatt, a computational chemist, and Dr. David Scott, a computer scientist at Intel Corporation. Discretization of the coupled integral equations for molecular collisions leads to a very large system of linear algebraic equations. The multilevel adaptive technique (MLAT), now widely used in computational fluid mechanics, will be combined with recursive and iterative techniques. First, a multichannel solution is obtained on a low level (coarse) grid. The basis (or grid) is then adapted to this solution and the coarse solution is projected or interpolated onto the new (adapted) basis. The scattering amplitudes on the fine grid are then developed through use of either the recursion method or the iterative technique. Applications to very large systems are possible because it is not necessary to store or invert a large matrix. The potential of these methods for parallel processing with be explored, and applications of the methods to several interesting chemical reactions will be undertaken.
