How Far Can We Go with Single-Configuration Quantum Chemistry?

Explore a comprehensive lecture by Peter Knowles from Cardiff University examining the limitations and potential extensions of single-configuration quantum chemistry approaches. Recorded at IPAM's Optimal Transport for Density Operators workshop at UCLA, this 57-minute presentation investigates how traditional quantum chemistry methods that begin with mean field models and single Slater determinants can be enhanced. Knowles discusses how electron correlation effects are typically introduced through perturbational methods, coupled-cluster theory, or density/density-matrix functionals, while acknowledging that strong correlation often requires multiconfigurational reference methods despite their computational cost and size extensivity challenges. The lecture delves into promising approaches for extending single-reference methods, including alternative coupled-cluster formulations, new perturbation theory forms, density matrix functionals, and machine learning correlation models. This technical presentation offers valuable insights for researchers working in computational chemistry and quantum physics.