John A. Pople has developed computational methods in chemistry. These are based on different descriptions of the wave function in the Schrödinger equation. He has created a theoretical model chemistry in which a series of increasingly refined approximations systematically approaches the exact solution to the quantum-mechanical equations. In this way it has become possible to control the accuracy of the calculations. The methods were made available to researchers through the GAUSSIAN computer program, today used for quantum-chemical computation within all areas of chemistry.