Efthimios Kaxiras is the John Hasbrouck Van Vleck Professor of Pure and Applied Physics at Harvard University, Massachusetts. He holds joint appointments in the Department of Physics and the School of Engineering and Applied Sciences, and is an affiliate of the Department of Chemistry and Chemical Biology. He is the Founding Director of the Institute for Applied Computational Science, a Fellow of the American Physical Society and a Chartered Physicist and Fellow of the Institute of Physics, London.