Configuration interaction

Configuration interaction methods use a linear expansion inside a Fock space as a wave function model: \[\begin{equation} \require{physics} \ket{\vb{c}} = \sum_{\vb{k}} c_{\vb{k}} \ket{\vb{k}} \end{equation}\] and then make use of the Rayleigh energy function: \[\begin{equation} E(\vb{c}, \boldsymbol{\eta}) = \ev{\hat{\mathcal{H}}(\boldsymbol{\eta})}{\vb{c}} \thinspace , \end{equation}\] to establish a variational theory.

Some forms of CI are covered in these knowdes:

• full CI;
• doubly-occupied CI.