Optical photons: different absorption as a function of wavelength

Dear @ceruttif ,
Thank you for your kindly help. I have another questions:
1.What is the absorption coefficient set to ensure that all primary photons are absorbed by POLYSTYR
and the generated secondary photons are not absorbed by POLYSTYR itself? (I have tried to set it up to 50, but there are no photons at the exit surface, I guess that generated secondary photons are absorbed by POLYSTYR itself )
Look forward to your help.

Evidently, the same absorption coefficient cannot at the same time ensure that all primary photons are absorbed and secondary photons are not. For this, different values are required as a function of the photon wavelength. One can implement them by means of the derivatives of the absorption coefficient, which the OPT-PROP card allows you to input, or the src/user/abscff.f function, where the absorption coefficient ABSCFF can be defined as a function of the photon wavelength WVLNGT (see the manual for both solutions).

Dear @ceruttif
I have do what you said, I use the first solutions, but there still does not have secondary photons.
I did like this:

  1. Primary photon wavelength=450nm, secondary photon wavelength=476nm, central wavelength=476nm;
  2. I used twice card of OPT-PROP,just see below:
    The 5th value calculated this:for primary photon, absorption coefficient=50, for secondary photon, absorption coefficient=0.01, derivatives of the absorption coefficient=(50-0.01)/[(450-476)/476-(476-476)/476]=-915.2
  3. wvlnsh.f please see the next attachment
    r-wvl.f (2.7 KB)
    I hope you can help me find the mistake,thank you!

In the M.inp file you uploaded (which by the way does not appear to be consistent with your last wvlnsh.f version, where you refer to a regcorex region not existing in the above M.inp), the central wavelength in POLYSTYR was defined as 450 nm, not 476 nm. The derivative you input in the last card works as expected if the central wavelength in POLYSTYR is defined as 476 nm.

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Dear @ceruttif

  1. I changed wvlnsh.f after your first answer.
  2. I misunderstood the central wavelength and changed it , it works now.
    Thank you for your help.