The Kramers–Wannier duality yields the exact location of the critical point for the Ising model on the square lattice.
He worked with Professor Eugene P. Wigner as a post-doc exchange student at Princeton in the academic year 1936/1937 and later taught at several American universities before a stint in industry from 1946 to 1960.
There he was in the Physical Electronics Group with colleagues such as William B. Shockley, Conyers Herring, John Bardeen, Charles Kittel, and Philip W.
[citation needed] He published a series of important papers on the properties of crystals, working with graduate students and visiting professors.
Additionally, he published widely read textbooks on solid-state theory and statistical mechanics.