MOLPRO

16 THE SCF PROGRAM 101
16.1.8 Printing options
PRINT|ORBPRINT=value
DEBUG=value
Number of virtual orbitals to be printed. If value=0, the occupied
orbitals are printed.
Option for debug print.
16.2 Defining the wavefunction
The number of electrons and the total symmetry of the wavefunction are specified on the WF
card:
WF,elec,sym,spin
where
elec
sym
spin
is the number of electrons
is the number of the irreducible representation
defines the spin symmetry, spin = 2 ∗ S (singlet=0, doublet=1,
triplet=2 etc.)
Note that these values take sensible defaults if any or all are not specified (see section 10.2).
16.2.1 Defining the number of occupied orbitals in each symmetry
OCC,n 1 ,n 2 ,...,n 8
To avoid convergence problems in cases with high symmetry, this card should be included whenever
the occupation pattern is known in advance. n i is the number of occupied orbitals in the
irreducible representation i. The total number of orbitals must be equal to (elec+spin)/2 (see WF
card).
16.2.2 Specifying closed-shell orbitals
CLOSED,n 1 ,n 2 ,...,n 8
This optional card can be used in open-shell calculations to specify the number of closed-shell
orbitals in each symmetry. This makes possible to force specific states in the absence of an
OPEN card.
16.2.3 Specifying open-shell orbitals
OPEN,orb 1 .sym 1 ,orb 2 .sym 2 ,...,orb n .sym n
This optional card can be used to specify the singly occupied orbitals. The number of singly
occupied orbitals must be equal to spin, and their symmetry product must be equal to sym (see
WF card). If the OPEN card is not present, the open shell orbitals are selected automatically.
The algorithm tries to find the ground state, but it might happen that a wrong state is obtained
if there are several possibilities for distributing the open shell electrons among the available
orbitals. This can also be avoided using the CLOSED card. If orb i .sym is negative, this orbital
will be occupied with negative spin (only allowed in UHF).