# CID CISDThese
method keywords request a Hartree-Fock calculation followed by configuration interaction
with all double substitutions (**CID**) or all single and double substitutions
(**CISD**) from the Hartree-Fock reference determinant [61,143,202].
**CIDS** and **CI** are synonyms for **CISD**. **FC**
All frozen core options are available with **CID** and **CISD**.
**Conver=N**
Sets the convergence calculations to 10^{-N} on the energy and 10^{-(N+2)}
on the wavefunction. The default is *N*=7 for single points and *N*=8
for gradients.
**MaxCyc=***n* Specifies the maximum number of
cycles for **CISD** calculations.
Energies,
analytic gradients, and numerical frequencies. **Transformation**
The
CI energy appears in the output as follows:
DE(CI)= -.48299990D-01 E(CI)= -.75009023292D+02
NORM(A) = .10129586D+01
The output following the final
CI iteration gives the predicted total energy. The second output line displays
the value of Norm(A). Norm(A)-1 gives a measure of the correlation correction
to the wavefunction; the coefficient of the HF configuration is thus 1/Norm(A).
Note that the wavefunction is stored in intermediate normalization; that is:
where Ψ^{0} is the Hartree-Fock determinant and has a coefficient
of 1 (which is what intermediate normalization means). Norm(A) is the factor by
which to divide the wavefunction as given above to fully normalize it. Thus:
The coefficient of the Hartree-Fock determinant in the fully normalized wavefunction
is then 1/Norm(A), the coefficient of singly-excited determinantΨ_{i}_{→}_{a}
is T_{ia}/Norm(A), and so on. |