31.9.1 Optimization criterion

CRIT,method;

Specifies the criterion for the optimization. method can be OVERLAP or ENERGY (OVERLAP is default). The former maximizes the normalized overlap with the CASSCF wavefunction:

$${\rm max}\left(\frac{\langle\Psi_{CAS}\vert\Psi_{VB}\rangle}{(\langle\Psi_{VB}\vert\Psi_{VB}\rangle)^{1/2}}\right)$$

and the latter simply minimizes the energy:

$${\rm min}\left(\frac{\langle\Psi_{VB}\vert\hat{H}\vert\Psi_{VB}\rangle}{\langle\Psi_{VB}\vert\Psi_{VB}\rangle}\right).$$