Michael Levitt walks to conduct interviews at his home in Stanford, California October 9, 2013. Three U.S. scientists, including Levitt, won the Nobel chemistry prize on Wednesday for pioneering work on computer programs that simulate complex chemical processes and have revolutionised research in areas from drugs to solar energy. The Royal Swedish Academy of Sciences, awarding the prize of 8 million crowns ($1.25 million) to Martin Karplus, Levitt and Arieh Warshel, said their work had effectively taken chemistry into cyberspace. REUTERS/Robert Galbraith (UNITED STATES - Tags: SCIENCE TECHNOLOGY POLITICS)