20.3.1 Defining the state symmetry

The number of electrons and the total symmetry of the wavefunction are specified on the WF card:

WF,elec,sym,spin

where

elec

is the number of electrons

sym

is the number of the irreducible representation

spin

defines the spin symmetry, spin$=2S$ (singlet=0, doublet=1, triplet=2, etc.)

Note that these values take sensible defaults if any or all are not specified (see section 2.13).

The input directives STATE, WEIGHT, LQUANT, SELECT, PUNCSF always refer to the state symmetry as defined on the previous WF card. If such a directive is found before a WF card has been given, the current state symmetry is assumed, either from a previous calculation or from variables [MC]SYMMETRY(1) and [MC]SPIN(1) (if these are defined). If any of these cards or a WF card is given, the variables STATE, WEIGHT, LQUANT, SELECT are not used, and the number of state symmetries defaults to one, regardless of how many symmetries are specified in variable [MC]SYMMETRY.