32.5 Recovering CASSCF CI vector and VB wavefunction

The appropriate MOLPRO records may be specified explicitly using the START directive (note, however, that use of the vbdump mechanism described in section 28.2.1 is preferable whenever possible):

START,ci,vb,orb,trnint;

ci: record name for the CASSCF CI vector. The CI vector must have been dumped previously using either of the SAVE, NATORB, CANONICAL, or LOCALI directives (see section 16.5.4). A default value for ci is determined from the most recent vbdump record(s).

Note that if the ci record is not found, only an energy-based optimization of the VB wavefunction can be carried out.

vb: record name for the valence bond orbitals and structure coefficients, as saved by a previous CASVB calculation. If the VB wavefunction was previously saved in the AO basis the orbitals will be projected onto the present active space (note that it is necessary to specify a record name for the molecular orbitals (orb below) for this to be possible).

orb: record name for the molecular orbitals defining the CASSCF wavefunction. This information is necessary if one wants to output the valence bond orbitals in the atomic orbital basis.

trnint: record name for the transformed CASSCF integrals. These are required for the energy-based criteria (i.e., if CRIT,ENERGY is specified), and can be saved inside MULTI by the TRNINT sub-command (see 16.8.7). The default record name, both here and in MULTI, is 1900.1.