Pople's major scientific contributions were in four different areas:
Statistical mechanics of water Pople's early paper on the
statistical mechanics of water, according to
Michael J. Frisch, "remained the standard for many years". This was his thesis topic for his PhD at Cambridge supervised by
John Lennard-Jones. Subsequently, he developed the methods of Complete Neglect of Differential Overlap (
CNDO) (in 1965) and Intermediate Neglect of Differential Overlap (
INDO) for approximate MO calculations on three-dimensional molecules, and other developments in
computational chemistry. In 1970 he and David Beveridge coauthored the book
Approximate Molecular Orbital Theory describing these methods.
Ab initio electronic structure theory Pople pioneered the development of more sophisticated computational methods, called
ab initio quantum chemistry methods, that use
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 suite of programs, including coauthorship of the first version, Gaussian 70. One of his most important original contributions is the concept of a model chemistry whereby a method is rigorously evaluated across a range of molecules. ==Awards and honours==