Collisions between of an atom with a symmetric top, with no inversion doubling

BASISTYPE = 18

System subroutine: systp1

Basis subroutine: hiba18_stp1.F90

Ref. S. Green, J. Chem. Phys. 64, 3463 (1976); M. H. Alexander, J. Chem. Phys. 77, 1855 (1982).

The definition of the integer system dependent parameters is as follows:

• NTERM: (the number of potential surfaces involved: this should be 1 in this case). This parameter can not be changed
• NUMPOT: an index representing the particular potential used. This variable is passed to the POT subroutine
• IPOTSY: cylindrical symmetry of potential. If the flag IHOMO = .True., only terms with mu equal to an integer multiple of IPOTSY can be included in the potential. Example: for NH3, IPOTSY = 3
• IOP: ortho/para label for rotational states of diatomic. If IHOMO = .True. then
  • if IOP = 1: only para states are included in channel expansion
  • if IOP = -1: only ortho states are included in channel expansion
• NINV: number of inversion doublets included:
  • if NINV = +1, only + inversion levels included
  • if NINV = -1, only - inversion levels included
  • if NINV = 2, both inversion levels included
• JMAX: the maximum rotational angular momentum included in the channel expansion
• EMAX: the maximum energy of a state to be included in the rotational state basis

The definition of the real system dependent parameters is as follows:

• BROT, CROT: rotational constants of symmetric top E(jk) = BROT *j (j + 1) + (CROT - BROT) k²