Collisions between of two ¹Σ Diatomics

BASISTYPE = 8

System subroutine: sy2mol

Basis subroutine: hiba8_2mol.F90

Ref. S. Green, J. Chem. Phys. 62, 2271 (1975); A. E. DePristo and M. H. Alexander, ibid. 66, 1334 (1977); M. H. Alexander, ibid. 73, 5135 (1980)

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
• NSYM: interchange symmetry of the included channels
• NUMJ: number of different J1/J2 pairs in channel list
• J1/J2: vector of length NUMJ containing packed index of rotational quantum number of each molecule with j₁ in the tens digit and j₂ in the ones digit.

For example, if NUMJ = 3, the program expects three J1/J2 values. Suppose these values are, successively, 00, 11, and 02. The calculation will then include all channels with the following pairs of molecular rotational angular momenta:

• j₁ = 0, j₂ = 0
• j₁ = 1, j₂ = 1
• j₁ = 0, j₂ = 2

Note that because of interchange symmetry, the last entry will automatically include all channels with j₁ = 2, j₂ = 0

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

• BROT: rotational constant
• DROT: centrifugal distortion constant

• HROT: second centrifugal distortion constant

  E(j) = B j (j + 1) - D [j (j + 1)]² + H [j (j + 1)]³