Talk:Multireference configuration interaction

Latest comment: 4 years ago by Libavius in topic CSFs are not necessarily determinants

For me choosing the configuration for the CI-space from some references is done always by taking singly, doubly, ... excited configurations relative to all reference. I do not know what is meant by "chosen by the program according to some perturbation theoretical ansatz according to a threshold provided by the user". Maybe this can be explained or taken into a new paragraph, describing this different/special method.

CSFs are not necessarily determinants

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The third sentence start with 'The higher excited determinants (also called configuration state functions (CSFs) or shortly configurations)...'. However, a CSF is a linear combination of determinants, and not always one determinant. The linear coefficients are called spin coupling coefficients. A CSF is equal to one determinant if and only if all orbitals are doubly occupied in the respective configuration. Libavius (talk) 17:08, 3 February 2020 (UTC)Reply