Parameter NUD and Flag NUCROS

NUD is the step size for the angular momentum projection in a Coupled States calculation. Scattering calculations are performed at every NUD value of the projection quantum number nu lying between (and including) NUMIN and NUMAX. For collisions involving a molecule with half-integer spin (flag FLAGHF=.TRUE.) then the total angular momentum and its projection is half-integer (although the parameter NU remains integer but is now equal to the projection minus 1/2). In this case the values of the projection quantum number range from NUMIN+1/2 to NUMAX+1/2 in steps of NUD.

If the flags WRXSEC and/or PRXSEC are .TRUE., then the program accumulates the contribution to the integral cross sections due to all partial waves lying between JTOT1 and JTOT2. If JTOTD=1, this is done by adding the degeneracy weighted sums of the squares of the T matrix at each partial wave.

In a CS calculation the integral cross sections can be determined in two ways:

If NUCROS = .FALSE., at each partial wave (for each value of ), the squares of the T matrix for each value of the projection index are summed to give a partial cross section indexed only in . Then

Then, similarly to a close-coupled calculation the program accumulates the contribution to the integral cross sections due to all partial waves lying between JTOT1 and JTOT2.

If NUCROS = .TRUE., the summation over partial wave is done before the summation over the values of the projection index. The first summation yields partial cross sections indexed only in the projection index. These are then summed to give the integral cross section.

In both cases if

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