John Pople
Sir John Anthony Pople (October 31, 1925 - March 15,2004) was a theoretical chemist. Born in England, he attended Bristol Grammar School, where an IT room is named after him. He came to the United States of America in the 1950s, where he lived the rest of his life, though he retained British citizenship. He received his B. A. (in 1946) and doctorate (in 1951) degrees in mathematics, 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. Pople considered himself more of a mathematician than a chemist, but theoretical chemists consider him one of the most important of their number.
His first major contribution was a theory of approximate molecular orbital (MO) calculations on pi electron systems in 1953, identical to the one developed by Rudolph Pariser and Robert G. Parr in the same year, and now called the Pariser-Parr-Pople (PPP) method. Subsequently, he developed the methods of Complete Neglect of Differential Overlap (CNDO) (in 1965) and Intermediate Neglect of Differential Overlap (INDO) (shortly later) for approximate MO calculations on three-dimensional molecules, and other developments in computational chemistry. He pioneered the development of more sophisticated computational methods, so called ab initio methods, that used basis sets of either Slater type orbitals or Gaussian orbitals to model the wave function. While in the early days these calculations were extremely expensive to perform, the advent of high speed microprocessors has made them much more feasible today. He was instrumental in the development of one of the most widely used computational chemistry packages, the "Gaussian(tm)" suite of programs. However, since 1991, Pople was excluded from development of the software. In fact, he was actually banned by Gaussian from even using their software.
In 1986 he moved from Carnegie-Mellon University in Pittsburgh, Pennsylvania, where his earlier accomplishments were made, to Northwestern University in Chicago, Illinois.
He received the Nobel Prize in Chemistry in 1998. He was knighted in 2003.