20.5.5 Natural orbitals

NATORB,[record,][options]

Request to calculate final natural orbitals and write them to record record. The default for record is 2140.2, or what else has been specified on an ORBITAL card, if present. By default, the orbitals are not printed and the hamiltonian is not diagonalized for the new orbitals The following options can be specified (in any order):

CI

Diagonalize the hamiltonian in the basis of the computed natural orbitals and print the configurations and their associated coefficients. This has the same effect as the GPRINT,CIVECTOR directive (see section 4.12. By default, only configurations with coefficients larger than 0.05 are printed. This threshold can be modified using the THRESH (see section 16.8.2) or GTHRESH (see section 4.11) options.

STATE=state

Compute natural orbitals for the specified state. state has the form istate.isym, e.g., 3.2 for the third state in symmetry 2. In contrast to earlier versions, isym refers to the number of the irreducible representation, and not the sequence number of the state symmetry. It is therefore independent of the order in which WF cards are given. The specified state must have been optimized. If STATE is not given and two or more states are averaged, the natural orbitals are calculated with the state-averaged density matrix (default).

SAVE=record

Request to save the civector(s) to the specified record.

PRINT=nvirt

Request to print nvirt virtual orbitals in each symmetry. By default, the orbitals are not printed unless the ORBPRINT option (see section 16.8.1 is present or the global GPRINT,ORBITALS (see section 4.12) directive has been given before. The PRINT option on this card applies only to the current orbitals.

Several NATORB, CANORB, and LOCORB cards (for different states) may follow each other. In contrast to earlier versions of MOLPRO the different orbital sets can all be stored in one dump record (but different records still work). See section 2.16 for information about dump records and how specific orbital sets can be requested in a later calculation.