Walter Kohn, 1998 Nobel Laureate in Chemistry and discoverer of the Density Functional Theory (DFT), died in 2016 at the grand age of 93. This book is the first ever biography of Kohn, who led a remarkable life and scientific career, not least the fact that his DFT theory has emerged as the underlying computational method for molecular simulation used throughout the physical and life sciences. Taking us on a compelling journey, Sir David Clary traces Kohn's early life in Vienna and his dramatic escape from the Nazis on the Kindertransport to England in 1939, followed by Kohn's internment as an 'enemy alien' and his transportation to Canada in 1940. His subsequent scientific career is discussed in detail, including his remarkable sabbatical in France when he discovered DFT, and his enduring efforts on peace initiatives and reduction of nuclear proliferation. An extraordinary story of a theoretical physicist winning the Nobel Prize in Chemistry, Walter Kohn is a sparkling chronicle of one of the great scientists of the 20th century who forever changed the way contemporary science is done.