Ab initio quantum chemistry methods

Ab initio quantum chemistry methods are a class of computational chemistry techniques based on quantum chemistry that aim to solve the electronic Schrödinger equation.^[1] Ab initio means "from first principles" or "from the beginning", meaning using only physical constants^[2] and the positions and number of electrons in the system as input. This ab initio approach contrasts with other computational methods that rely on empirical parameters or approximations. By solving this fundamental equation, ab initio methods seek to accurately predict various chemical properties, including electron densities, energies, and molecular structures.

The ability to run these calculations has enabled theoretical chemists to solve a range of problems and their importance is highlighted by the awarding of the 1998 Nobel prize to John Pople and Walter Kohn.^[3] The term ab initio was first used in quantum chemistry by Robert Parr and coworkers, including David Craig in a semiempirical study on the excited states of benzene.^[4][5] The background is described by Parr.^[6]