Towards reliable beyond-zero-sum density functional theory: Wavefunction-inspired DFT meets DFT-inspired wavefunctions

Abstract

This chapter discusses recent efforts towards reliable and broadly accurate electronic structure approximations. We seek to go beyond the “zero-sum game” of approximate density functional theory (DFT), by combining ideas from DFT and ab initio density functional theory. Standard DFT treats a reference system of noninteracting electrons, corrected by an approximate density functional for many-body electron-electron interactions. Our methods treat a reference system of partially interacting electrons, corrected by an approximate density functional for the remaining interactions. Our projection-based formalism lets us select which electron-electron interactions are introduced into the reference system. This lets us balance the strengths and weaknesses of an approximate reference system wavefunction and an approximate density functional. Our results build towards more practical and broadly accurate electronic structure methods.