John Perdew's best-known scientific contributions are in the field of
density functional theory (DFT). He was introduced to DFT by his postdoctoral supervisors at University of Toronto and Rutgers, before it became widely used. Perdew was one of the early pioneers of density functional theory, helping it become accurate enough for calculations in
quantum chemistry,
materials science, and
geoscience. He made important contributions to the exact
adiabatic connection fluctuation dissipation theorem (ACFD) for the (exchange)-correlation energy, the derivative discontinuity and its contribution to the fundamental gap, scaling and other exact constraints on the functionals, the self-interaction correction, the nonempirical generalized gradient approximation (GGA), and the nonempirical meta-GGA. Perdew's Jacob's Ladder scheme has been picked up by other researchers in DFT and progress higher up the ladder continue to appear in the field's scientific literature. Perdew continues DFT research in his role at Tulane University. His current research interests include the construction of a better
meta-GGA and improved descriptions for strong correlation and for the
van der Waals interaction. ==Impact on field==