Methods of quantum mechanical calculations independent of any experiment other than
the determination of fundamental constants. The methods are based on the use of the
full Schroedinger equation to treat all the electrons of a chemical system. In practice,
approximations are necessary to restrict the complexity of the electronic wavefunction
and to make its calculation possible.
This definition supersedes an earlier definition of
IUPAC. Compendium of Chemical Terminology, 2nd ed. (the "Gold Book"). Compiled by
A. D. McNaught and A.Wilkinson. Blackwell Scientific Publications, Oxford (1997).
XML on-line corrected version: http://goldbook.iupac.org (2006-) created by M. Nic,
J. Jirat, B. Kosata; updates compiled by A. Jenkins. ISBN 0-9678550-9-8. https://doi.org/10.1351/goldbook