Ground State of Helium

In 1958, Pekeris published an article entitled, “Ground state of two-electron atoms,” which was to become his most cited work. It displayed an unusual degree of proficiency in programming and exploited to their extreme the physical capacities of WEIZAC. At the core of this contribution were a series of daunting differential equations that were solved numerically, using code written by the young Yigal Accad, who in 1973 would complete a PhD on “Ocean Tides” under Pekeris.