1998 Nobel Prize in Chemistry(2)
Reason for Award
for the development of computational methods in quantum chemistry
Laureates
United Kingdom of Great Britain and Northern Ireland
Explanation
Molecules are often shown as balls and sticks, yet in reality their electrons form cloudy shapes. John Pople invented fast computer methods to draw and study those clouds. Now we can predict how a drug or plastic will behave before we make it. It is like using a mold to test a cookie’s shape before baking—scientists test molecular shapes with Pople’s programs.
Related Keywords
Gaussian basis set
A representation that approximates atomic orbitals as linear combinations of Gaussian functions. Analytical integrals allow fast computation. Hierarchical families such as 6-31G and cc-pVTZ let users trade accuracy for cost depending on molecular size.
Hartree–Fock method
A basic ab-initio approach treating electron interaction in a mean-field way. Serves as the reference for post-HF correlation methods (MP2, CI, CCSD). Pople’s code automated HF calculations and extended them to large molecules.
GAUSSIAN program
One of the most widely used quantum-chemistry packages. A single input format can call many methods. Extensively applied in pharmaceuticals, materials, and environmental science, assisting early-stage experimental design.
MP2 method
Second-order Møller–Plesset perturbation theory. Recovers a portion of the correlation energy missing in HF at moderate cost. Captures dispersion and steric effects and, with Gaussian bases, predicts reaction energies within about 1–2 kcal/mol.
composite methods (G2/G3)
Multistep calculation protocols proposed by Pople. After geometry optimization with a small basis, larger bases and correlation corrections are added stepwise, plus empirical terms, to yield high-accuracy energies. Achieved “chemical accuracy” when compared with thermochemical data.
quantum chemistry software
Programs that compute molecular electronic structure. Examples include GAUSSIAN, GAMESS, ORCA, each with different input languages and implementations. Pople’s design philosophy influenced many later codes.
molecular orbital
Orbitals occupied by electrons in a molecule. Expressed via linear combinations of atomic orbitals (LCAO); their energy ordering dictates reactivity. Pople’s methods made MO visualization feasible even for large molecules.