All CASVB sub-commands may be abbreviated by four letters.
The general input structure can be summarized as follows:
Items a) and b) should precede everything else in the input;
apart from this, commands may come in any order.
- For generating representations of CASSCF wavefunctions, the program
is invoked by the command CASVB.
For variational optimization of wavefunctions it is normally invoked
inside MULTI by the sub-command VB (see 19.10).
- Definition of the CASSCF wavefunction (not generally required).
- Definition of the valence bond wavefunction.
- Recovery and/or storage of orbitals and vectors.
- Manual input of starting guess (optional).
- Optimization control.
- Definition of molecular symmetry and possible constraints on
the VB wavefunction.
- Wavefunction analysis.
- Further general options.