The command FLUX requests the determination of the collision or photodissociation flux as a function of R using using data stored during a previous calculation. For more details on the definition and determination of the flux see:

M. H. Alexander, J. Chem. Phys. 95, 8931 (1991); 96, 6672 (1992). D. E. Manolopoulos and M. H. Alexander, J. Chem. Phys. 97, 2527 (1992); M. H. Alexander, C. Rist, and D. E. Manolopoulos, J. Chem. Phys. 97, 4836 (1992).

The command line syntax is

FLUX,{jobnam},IFLUX,{additional variables}

where

• {jobname}: the jobname under which the wavefunction information from the previous calculation is stored, as the file {jobname}.wfu

⚠️ In order to create the {jobname}.wfu file, the previous calculation must have been carried out with the flags WAVEFL and AIRYFL both set .TRUE.

• IFLUX =
  • 1: for a determination of the fluxes in the diabatic (asymptotic) basis
  • −1: for a determination of the fluxes in the locally adiabatic basis
  • 2: for a determination of the adiabatic energies (see also the EADIAB command)
  • −2: for fluxes summed over the sign of the additional channel index
  • 3: for fluxes in coordinate space
  • 4: for determination of the transformation matrix C(R), defined in Eq. (6) of the help file describing the close coupling method

If IFLUX = −1,1, or −2 then the {additional variables} are THRESH, IPRINT, DAMP, INITIAL-J, INITIAL-L, and INITIAL-IND. These are defined as follows:

• THRESH: If the local wavevector in any channel is less than THRESH, then the wavefunction component associated with this channel is killed off. The default value of THRESH is 0 for scattering calculations, and -1.e+9 for photodissociation calculations

• IPRINT: Normally, fluxes are not printed inside of any energetically closed region. To print these out set IPRINT not equal to zero. The default value of IPRINT is 0 for scattering and 1 for photodissociation

• DAMP: the damping factor for closed channel components (the default value is one)

• INITIAL-J: the rotational angular momentum of the initial channel

• INITIAL-L: the orbital angular momentum of the initial channel

• INITIAL-IND: the value of the additional index of the initial channel

• In addition, channel fluxes are printed out ONLY for those channels which are specified in the arrays JOUT and INDOUT.

❗For a photodissociation calculation it is not nessary to specify THRESH, IPRINT, DAMP, INITIAL-J, INITIAL-L, or INITIAL-IND. In this case the command line should be

FLUX,JOB,IFLUX

If IFLUX = 3 then the {additional variables} are NR, RMIN, DR, THRESH, IPRINT, and DAMP, where

• NR:

  NR

  is the number of coordinate space points at which the flux is to be determined

  • if NR > 0, then the calculated flux is a sum over the flux associated with all channels with positive values of the additional index
  • if NR < 0, then the calculated flux is a sum over the flux associated with all channels with negative values of the additional index

• RMIN: Minimum value of the internal coordinate r

• DR: Step size in the internal coordinate r

• THRESH: as defined above

• IPRINT: as defined above

• DAMP: as defined above

❗Coordinate state fluxes will be determined for all values of the internal coordinate r ranging from RMIN to RMIN+(NR -1) DR

If IFLUX = 4 then {additional variables} designates

• nstate: The number of states for which the asymptotic → locally adiabatic transformation matrix is to be printed out

• Rmin: The minimum value of R at which the asymptotic → locally adiabatic transformation matrix is to be printed

• DR: The step size

• Rmax: The maximum value of R at which the asymptotic –> locally adiabatic transformation matrix is to be printed

If the variable DR is ≤ 0, then the transformation matrix is printed out just for R=Rmin. Otherwise, the transformation matrix is printed out for R = Rmin : DR : Rmax.

❗nstate cannot exceed 12, it will be truncated if the input value exceeds 12.

⚠️ Fluxes are determined at all values of R lying between RENDLD and RENDAI, with the grid size and spacing controlled by the same parameters which govern the AIRY integration, namely SPAC, FSTFAC, TOLAI, and RINCR.

⚠️ The determination of collision and photodissociation fluxes should be attempted only if you have a sophisticated understanding of the time-independent quantum description of molecular collisions.