In unrestricted
Hartree–Fock method, the wavefunctions obtained are eigenfunctions of the Hamiltonian and
the
spin projection
operators, but not eigenfunctions of the
operator. As a result, the wavefunctions of the doublet systems are spin-contaminated
to some extent by admixtures of quartet, sextet, and higher spin states. The eigenvalues
of the
operator are given as a measure of the spin
contamination.
Source:
Cite as:
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.
