[Pw_forum] Raman intensity with or without ASR

Antoine JAY antoine.jay at polytechnique.edu
Mon Feb 2 18:20:35 CET 2015

Dear all,
Thank you for your first answer.

I have applied ASR simple and crystal which give the quite same results on
the variation of the eigenvectors. The difference on the deplacement of
normal modes read from dynmat.out are less than 10^-5.
So the Raman intensities are the same (diff<2%).

But the difference on the eigenvectors with and withour ASR is higher
Even if this is still a small difference, it's enough to highly change the
resulting intensities (more than 50%). Of course, high intensities are
still high and weak are still weak.

Question: Why are the intensities calculated with the eigenmodes before
the ASR better calculated?
Is it consistent to impose ASR when I'm looking at a optical property? (I
don't care having exactelly zero frequencies (before ASR 2,6,8 cm^-1)  of
acoustics modes at Gamma point)

Thanks for all

Antoine JAY
Doctorant (PhD student)
Laboratoire des Solides Irradiés

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