Slater determinants in Configuration Interaction

[saleheen]

How does one create the single or doubly excited slater determinants in CI? What I mean is using HF, when I get the MO's, I can create the HF slater determinant which runs over electrons in rows and orbitals in columns. What is the form of single or doubly excited slater determinants? Sorry if I'm making the question unclear.

 

[DrDu]

In HF, you construct the single Slater determinant from the n orbitals of lowest energy. However, the HF equations, yield an infinite number of orbitals which form a complete set. If you replace one or more of the n orbitals in the HF Slater determinant by one or several of these excited orbitals with higher energy, you get the additional Slater determinants for CI.