*CONFIGURATION INPUT

Purpose:

To specify the configuration part in MCSCF and CI calculations.

.CAS SPACE

READ (LUINP,*) (NASH(I),I=1,NSYM)
CAS calculation: Active orbitals in each symmetry.

.ELECTRONS

Required.
READ (LUINP,*) NACTEL
Number of active electrons (the number of electrons to be distributed in the active orbitals). The total number of electrons is this number plus two times the total number of inactive orbitals.

.INACTIVE ORBITALS

Required.
READ (LUINP,*) (NISH(I),I=1,NSYM)
Number of inactive orbitals each symmetry.

.RAS1 ELECTRONS

READ (LUINP,*) NEL1MN,NEL1MX
Minimum and maximum number of RAS1 electrons; this can alternatively be specified with ".RAS1 HOLES"

.RAS1 HOLES

READ (LUINP,*) NHL1MN,NHL1MX
Minimum and maximum number of holes in RAS1; alternative to ".RAS1 ELECTRONS"

.RAS1 SPACE

READ (LUINP,*) (NAS1(I),I=1,NSYM)
RAS calculation: RAS1 orbital space

.RAS2 SPACE

READ (LUINP,*) (NAS2(I),I=1,NSYM)
RAS calculation: RAS2 orbital space

.RAS3 ELECTRONS

READ (LUINP,*) NEL3MN, NEL3MX
Minimum and maximum number of RAS3 electrons

.RAS3 SPACE

READ (LUINP,*) (NAS3(I),I=1,NSYM)
RAS calculation: RAS3 orbital space

.SPIN MULTIPLICITY

Required for MCSCF and CI wave functions.
READ (LUINP,*) ISPIN
For CSF basis: state spin multiplicity = $2S + 1$, where $S$ is the spin quantum number.
For determinant basis this option determines the minimum spin multiplicity. The $M_S$ value is determined as (ISPIN-1)/2.

.SYMMETRY

Required for MCSCF and CI wave functions.
READ (LUINP,*) LSYM
Spatial symmetry of CI and/or MCSCF wave function

Comments:

SYMMETRY Specifies total spatial symmetry of the wave function in $D_{2h}$ symmetry or one of its subgroups: $C_{2v}$, $C_2h$, $D_2$, $C_s$, $C_i$, $C_2$, $C_1$. The symmetry number of wave function follows MOLECULE output ordering of symmetries ($D_{2h}$ subgroup irreps).

CAS and RAS are exclusive and both cannot be specified in the same MCSCF or CI calculation. One of them must be specified.