Basis Subroutine and System Specific Parameters: Collisions between a ²Sigma Molecule and a Spherical Atom

System subroutine: sy2sg

Basis subroutine: hiba2sg.f

NTERM (the number of potential surfaces involved: this should be 1 in this case). This parameter can not be changed

NPAR: number of symmetry components included

If NPAR = 1, just = +1 states are included
If NPAR .ne. 1, both = +1 and = - 1 states are included


NRMAX: maximum Hund's case (b) rotational quantum number N.

ISYM: reflection symmetry of electronic state

ISYM= +1 for ⁺ states
ISYM = -1 for ^- states


IGU: inversion symmetry of states included in expansion.

IGU = +1 for gerade states
IGU = -1 for ungerade states
for heteronuclear molecules IGU should be +1

ISA: Nuclear permutation symmetry (s/a label) of states included in expansion.

If the flag IHOMO is .TRUE., then only s states will be included if ISA = +1 and only a states if ISA = -1

BROT: rotational constant
GSR: spin-rotation constant
DROT: centrifugal distortion constant
HROT: second centrifugal distortion constant