Computational chemistry

Computational chemistry is the application of computation to the solution of problems in chemistry. This includes finding solutions to the Schrödinger equation, which determines stable configurations of atomic particles and therefore what molecules are physically realizable. Another instance would be molecular dynamics, which models the motions of molecules in response to the various forces acting upon them: electrostatic attraction and repulsion, etc.

The equations used to determine the stability of a proposed molecular structure analyse the interactive forces between every atom in the molecule. Thus, as the number of atoms in the molecule increases, the number of equations that must be solved goes up exponentially. With so many calculations to be performed, the realistic use of this approach in chemistry requires vast amounts of computing power, and supercomputers and distributed computing are used. Another way of simplifying the (still complex) calculation is not to take all atoms into consideration, but to, for example, omit the interactions between "distant" atoms or to keep some parts of large molecules rigid.

This approach is one of the fastest-growing areas of chemistry in the pharmaceutical industry. Instead of having to synthesise and test thousands of possible new drugs in the laboratory, the first stage of elimination can be performed on the computer. This has the twin advantages of saving a lot of money and of reducing the dependence on animal testing for understanding chemical interactions in biological systems. In the future it may be possible to eliminate animal testing using this knowledge.