95-61117 Johnson This Small Business Innovation Research Phase I project will focus on the development of analytic techniques for the integration of density functionals. In recent years, Density Functional Theory (DFT) has emerged as an accurate alternative first-principles approach to quantum mechanical molecular investigations, which is cost-effective compared with conventional correlated methods. Unfortunately, the approximate density functionals used in practice are quite complicated and numerical quadrature must be used for their integration. There are difficulties inherent to such grid-based methods which do not arise in methods where all the requisite integrals are evaluated analytically, for example, as in Hartree-Fock theory. Unless great care is taken in the handling of the molecular grid, undesirable effects manifest themselves in the calculation. These various difficulties can be rigorously handled, but their improper treatment is a source of problems in most implementations. The goal of the Phase I feasibility study is to develop an analytically integrable density functional which yields a theoretical model chemistry similar to that of the Dirac functional. We will implement the resulting functional within the firm s quantum chemistry computer program. A practical analytic method would eliminate the spurious effects described above and at the same time would be quite likely to improve the computation time for small and medium-sized systems. The commercial benefits are apparent by measuring the substantial increase in both the quality of the results and the efficiency of the system resulting in increased research productivity and cost effectiveness.
