Otto Sankey

Otto F. Sankey, Emeritus Regents Professor of Physics and Astronomy at Arizona State University and APS Fellow, was born on 11 January 1951 and died on 21 March 2020 at the age of 69 after a prolonged battle with cancer. He is survived by his wife Debbie; three daughters, Stephanie, Holly, and Robin; and several grandchildren.

Otto was many things: a brilliant theorist, a beloved friend, and an outstanding mentor. But above all, he was an original scientist, never content to develop the next iteration of a fashionable theory or to follow the latest scientific fad. Otto relished being on the “scientific edge.” Otto will surely be most remembered for pioneering local orbital ab initio molecular dynamics and the code FIREBALL. His paper with graduate student D. Niklewski was a scientific tour de force elucidating the links between density functional theory, Car–Parrinello methods, and tight-binding. His characteristically named “fireballs” were pseudoatomic orbitals confined to a finite volume. He showed that these were in many cases an ideal basis set for local orbital simulations, and these were adopted later by the highly successful code SIESTA. Altogether, FIREBALL provided an efficient yet accurate approximate solution to the Kohn–Sham equations that led to myriad new insights into materials from buckyballs to DNA. Otto also made memorable contributions to transport theory, high-pressure simulations of materials, and in recent years, biological materials, among them DNA. Otto rediscovered the Breit–Wigner formula in a molecular context to explain long-range transport in DNA. His detailed DFT calculations were critical to designing the molecules needed for DNA sequencing by recognition tunneling. In view of the current pandemic, we highlight a paper of Sankey and Dykeman in Physical Review Letters in 2008 revealing how a virus could be destroyed by laser irradiation. The idea was to work out the normal modes of the capsid (essentially, the exterior shell containing the virus’s genetic material) and so calculate the wavelength of light needed to destroy the virus.

Otto was a beloved friend and mentor. The three of us, but also dozens of others, felt our lives transformed by his guidance and encouragement.