Mail:
Dept. of Chemistry
Ohio State University
100 W. 18th Ave.
Columbus, OH 43210
Office:
412 CBEC
Email:
herbert@
chemistry.ohio-state.edu
Fragment-based quantum chemistry is an increasingly popular means to extend electronic structure theory to large systems. A variety of fragment-based approaches exist, and we provide an overview of several that we have developed recently. Our goal is not only to extend quantum chemistry calculations to large clusters and molecular liquids, but also to achieve "chemical" accuracy of ≤ 1 kcal/mol with respect to the best available ab initio benchmarks. We outline several routes to achieving this level of accuracy. The first is a generalization of the traditional many-body expansion to include situations where the monomer units overlap, which provides good accuracy for clusters of polar monomers even when the many-body expansion is truncated at the two-body level. A second method generalizes the technique of symmetry-adapted perturbation theory to many-body clusters, and works especially well when combined with empirical dispersion potentials. Each of these methods is embarrassingly parallelizable and thus amenable to sizable clusters.