Eric derives and implements new theoretical models and related algorithms for the electronic structure of molecules and materials. In particular, Eric is interested in approximations that retain their accuracy even in systems where mean-field-based methods such as density functional theory and even coupled cluster theory are grossly incorrect due to the breakdown of the statistically independent particle approximation. Advances in this area are needed in order to improve our predictive power over chemical catalysis, molecular light harvesting, and materials with non-innocent d or f orbitals.