This Small Business Innovation Research (SBIR) Phase II project seeks to construct new density functionals for use in quantum chemistry. All of the popular functionals in use today lead to difficult three-dimensional integrals that cannot be computed exactly and which are estimated approximately using large three-dimensional grids. This project approaches the problem by devising functionals which, by construction, can be integrated exactly and which, therefore, require no grids. The work will proceed in a number of stages and should yield "gridless" functionals for the exchange and correlation energies. It should also yield "gridless" functionals for the kinetic energy. The results will be published in respected journals and presented at international scientific conferences. The use of gridless density functionals offers two advantages over present methods: (1) The results will not be contaminated by "grid noise", the error introduced by the imperfect quadrature afforded by a finite numerical grid. (2) Exact integration is much more efficient than quadrature on a three-dimensional grid (with thousands of grid points per atom) and, as a result, gridless calculations should require much less computing time than grid-based ones. The new functionals, will be implemented within the software package and made available commercially to computational scientists in a future release. Because gridless density functional calculations will be both more numerically robust and more computationally efficient than grid-based calculations, their availability will allow computational scientists to undertake first principles quantum mechanical studies of larger and more complicated systems than were previously accessible. This will benefit research in biochemistry, pharmaceuticals, new materials and elsewhere.
