The Theoretical and Computational Chemistry Program is supporting Professor D. Kouri of the University of Houston. In this next grant period he we will continue to pursue computational implementation and testing of the Time-Independent Wavepacket Divide-and-Conquer (TIWDC) approach. The immediate objectives are: a) Testing the DC-procedure whereby the initial arrangement is also uncoupled from the strong interaction region. b) Testing the DC strategy for uncoupling the vibrational-rotational, pure rotational, and elastic final state interaction regions so that the maximum benefit of the approach can be realized. c) Applying the DC procedure to H+O2 -> OH+O in order to try and carry out the first ever completely ab initio calculation of state-to-state reaction cross sections for the system as a function of energy. He also will carry out the first full 3D tests of the TIWDC method for photodissociation of HOD, with emphasis on a comparison with experiment when the HOD is vibrationally hot. Secondly, he will continue development of the distributed approximating functionals (DAFs), including the exploration of a new class of DAFs that are related to various interpolation schemes. These investigations will also study the fitting of multidimensional potential energy surfaces using finite amounts of ab initio input data, with particular emphasis on electronically non-adiabatic systems. Third, he will continue studies of a new method being developed for diagonalizing extremely large matrices with very dense eigenspectra. Finally, he will begin work on developing and testing new approximation methods for solving the quantum equations for reactions involving more than 4 atoms in order to simulate more complex chemical systems. The research supported here focuses on developing robust, efficient, and highly stable methods for solving the partial differential equations which are used to describe fundamental chemical reaction processes. Because of the enormous complexity of the equations, solutions are feasible only by using the most powerful, high-speed, large-memory computers. However, the development of a detailed understanding of the elementary chemical reaction process can open up the possibilities of controlling chemical reactions in order to maximize desired products. These studies are also used in simulating numerically fundamental processes that occur in the earth's atmosphere, in order to understand and better deal with pollution. Such studies also find application in modeling the detailed chemistry of combustion in order to develop pollution-free propulsion systems. In addition, some of the techniques being developed can also be used to solve other, enormously important partial differential equations. Thus, the techniques being developed show great promise for making it possible to solve equations ranging from long term weather forecasting, to other equations used to model combustion.
