CASSCF CASSCF = Complete Active Space Self Consistent Field theory
In CASSCF chemically important "active' orbitals are selected. These lead to the
MCSCF configurations obtained by a full CI within that active space.
In CASSCF a complete CI is performed over the active space.
In quantum chemistry, a Complete Active Space is a type of classification of molecular orbitals. Spatial orbitals are classified as belonging to three classes:
With CASSCF static correlation is accounted for to first approximation. Static correlation is important to take into account when describing bond dissociations for example.
Dynamic correlation is not accounted for in CASSCF. This effect is usually taken care of as a perturbation of the CASSCF wavefunction as CASPT2.