Markus Pössel (User name: Mapos) · CC BY-SA 3.0

Walter Kohn built the mathematical framework, density functional theory, that made it possible to calculate the electronic structure of molecules and materials without solving the full quantum many-body problem — a simplification that turned quantum chemistry into a practical, everyday tool across materials science and chemistry. The work earned him the 1998 Nobel Prize in Chemistry, shared with John Pople. Kohn spent his career as an Austrian-American theoretical physicist and chemist, working mainly in the United States.