Walter Kohn and the Australian Psyche

Abstract

My encounters with Walter Kohn began in 1969 when I came from Australia to La Jolla, California to begin a physics PhD. I didn’t end up being supervised by Walter and didn’t have anything to do with Density Functional Theory in my doctoral research, but in due course I did take Walter’s Advanced Solid State class. That was undoubtedly the best lecture series I’ve ever attended. For every topic, Walter used his unique insight to focus on the essential elements necessary for a true physical understanding, together with just enough detail to make things concrete from a student perspective. Part of the charm was in the homework. I had never thought I would enjoy homework in quite this way. There were no “plug-ins” - each problem required just a small extension of the basic theory that he had presented, ensuring that you had to understand the subject properly. Then you were led to apply your extended theory to a realistic physical situation. Finally you had to go to the recent literature to confirm your numbers against experiment. It cannot have been easy to find problems of this style that were completely up-to-date yet feasible for graduate students within a reasonable time scale. It was worth it, though: working those problems gave us a tremendous sense of achievement, and of course we really learnt our stuff.