A reply to the previous post and a new question about flat particles

[zhengxin song]

Dear Amos,

Please forgive me for having to reply to you by creating a new post. I deleted my reply because it had some errors in its content. Then I tried to reply again but found it wouldn't post.

Thank you very much for your guidance! According to what you said I have modified and run my program successfully and changed my layer system. But I have some other questions.

A few days ago I read your article:Extending the applicability of the T-matrix method to light scattering by flat particles on a substrate via truncation of sommerfeld integrals. I would like to calculate the data in figure 7, as shown below. Are your differential scattering cross section data in figure 7 corresponding to azimuthal angle of 0 and π? In that case the data I calculated with smuthi has a good fit with the first figure, but when I change the parameters to calculate the data in the second figure, I get smaller results than in the figure. I tried to calculate the other figures again and the results were also on the small side. This is my program below, can you help me to correct the error? The value of neff_max in it is obtained according to the formula of neff vs. κ, and the formula of κ given in the article, and I'm not sure if this is the right thing to do.

I would greatly appreciate your help.

Best regards,

Song Zhengxin

[Amos Egel]

Dear Song Zhengxi,

I am happy to hear that you managed to get your script correctly running.

In your script I cannot find an error. It seems to me that in order to reproduce the results of that publication a higher value of l_max is needed, try for example l_max=20. In the publication we stated that the results were created with l_max=10, but maybe there was something wrong with that ...

Good observation on your side!

Sorry for the confusion.

Cheers, Amos

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Smuthi project repository: https://gitlab.com/AmosEgel/smuthi
Online documentation https://smuthi.readthedocs.io/en/latest/
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[zhengxin song]

Dear Amos,

Thank you again! When I set the value of lmax to 20, the results of my program fit the data in your article much better than before! By the way, can I ask you some other questions?

When I calculate the reflectance of randomly distributed particles in a medium, I include an intermediate layer of finite thickness, which has an imaginary part of the refractive index. Although the value of the imaginary part is not significant, its influence needs to be taken into account. At certain values of wavelength, my program gives the error: complex angles are not allowed, while at other values of wavelength this error does not occur. By debugging the program at the time of the error, I found that in the periodic_pwe_to_ff_conversion function, the imaginary part of a polar angle of about 1e-35 was calculated. This value is very small and insignificant, can I ignore this imaginary part and continue the calculation? Will this lead to incorrect results?

I would be grateful if you could take the time to give me some guidance.

Best regards,

Song Zhengxin