John A. Pople (1925-) is a theoretical chemist. Born in England, he came to the United States of America in the 1950s, where he has resided since the 1950s, though retaining British citizenship. He received his doctorate in mathematics in 1951, from Cambridge University in the United Kingdom. His thesis was, however, on a topic that would generally be considered chemistry: the bonding structures of water.
His first major contribution was a theory of approximate molecular orbital (MO) calculations on pi electron systems, identical to the one developed by Rudolph Pariser and Robert G. Parr, and now called the Pariser-Parr-Pople (PPP) method. Subsequently, he developed the methods of Complete Neglect of Differential Overlap (CNDO) and Intermediate Neglect of Differential Overlap (INDO) for approximate MO calculations on three-dimensional molecules, and other developments in computational chemistry.
In 1986 he moved from Carnegie-Mellon University in Pittsburgh, Pennsylvania, where his earlier accomplishments were made, to Northwestern University in Chicago, Illinois, where he is now a professor.
He received the Nobel Prize in Chemistry in 1998.