The user documentation for Hibridon
JTOT1 is the initial value of the total angular momentum in a CC calculation. For collisions involving a molecule with half- integer spin (flag FLAGHF) then the true total angular momentum is equal to Jtot+1/2.
For collisions of a molecule with an uncorrugated surface, you should set JTOT1 = 0.
JTOT2 is the final value of the total angular momentum in a CC calculation or the the orbital angular momentum (L) in a CS calculation. In the calculation of integral and/or differential cross sections, you must ensure that the parameter JTOT2 has been set large enough so that increasing its value will not significantly change the cross section(s) of interest.
For collisions of a molecule with an uncorrugated surface, you should set JTOT2=0.
JTOTD is the step size for the total angular momentum in a CC calculation or the the orbital angular momentum (L) in a CS calculation. Scattering calculations are performed at every JTOTD value of JTOT (or L) lying between (and including) JTOT1 and JTOT2. For collisions involving a molecule with half-integer spin (flag FLAGHF) then the total angular momentum is half integer (although remains integer). In this case the true values of Jtot range from JTOT1+1/2 to JTOT2+1/2 in steps of JTOTD.
If the flags WRXSEC and/or PRXSEC are .true., 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. If, however, JTOTD > 1, then a Simpson’s rule scheme is used to interpolate the missing T-matrix elements in this sum.
For collisions of a molecule with an uncorrugated surface, you should set JTOTD = 0.