Quantum mechanical method for the calculation of open-shell excited states.
The method accurately describes low-lying multi-configurational electronic states
and triradicals in an efficient and robust single-reference scheme.
The target low-spin
states (e.g., S = 0 or S = 1/2) are described as spin-flipping
excitations (S = −1) from a well-behaved high-spin
(e.g., S = 1 or S = 3/4). By employing theoretical models of increasing
complexity for the reference (e.g., SCF
the accuracy in the target states’ description can be systematically improved.
methods result in multistate single-step computational schemes, e.g.,
several low-lying states can be computed in a single calculation that includes
both dynamical and non-dynamical correlation effects.
PAC, 2007, 79, 293
(Glossary of terms used in photochemistry, 3rd edition (IUPAC Recommendations 2006))
on page 427
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