Alkali metals like potassium and sodium have been hiding a mathematical secret that threw off physics calculations for decades.
April 29, 2026
Original Paper
Kohn-Sham Hamiltonian from Effective Field Theory: Quasiparticle Band Narrowing from Frozen Core Dynamics
arXiv · 2604.25199
The Takeaway
Theoretical models for how electrons move in metals consistently overshot experimental measurements by up to 35 percent. Physicists assumed this error was an unfixable flaw in Density Functional Theory, which is the most popular framework for simulating new materials. A new renormalization factor accounting for frozen core dynamics finally corrects this long-standing discrepancy. This fix means engineers can now predict the electronic behavior of metals with much higher accuracy. It transforms one of the most used tools in material science from a rough approximation into a precise instrument for designing future electronics.
From the abstract
Kohn-Sham (KS) eigenvalues are routinely compared with angle-resolved photoemission (ARPES) and used as input for many-body methods, yet density functional theory (DFT) assigns them no physical meaning. For alkali and alkaline-earth metals, KS bandwidths overestimate ARPES measurements by 20-35%, a discrepancy that persists across all exchange-correlation functionals. We construct an effective field theory (EFT) of the inhomogeneous electron gas and show that two conditions imply KS bands are th