Kohn-Sham density functional theory provides a formally exact correction to a model system of noninteracting electrons. Our Adiabatic Projection approach generalizes this to model systems whose electron-electron interaction operator is projected onto an active space. This provides projected-exchange-correlation (PXC) density functionals correcting small-active-space ab initio theory. The PXC functionals are formally exact by the Hohenberg-Kohn theorems, avoid double-counting of correlation, and recover conventional DFT and full ab initio theory in the appropriate limits. The present work presents approximate PXC functionals applied to full configuration interaction and truncated coupled cluster wavefunctions expanded in minimal active spaces.  Numerical results show promise for practical applications in large systems.

Formally exact DFT corrections for Ab initio theory in small active spaces

Fall 2022 abstracts, posters, and presentations will launch in mid-September.

ACS Fall 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.