Imaginary part of SHG calculation

[pangrt]

Dear developers,
I am running SHG with Yambo and got the SHG chi, and how could I obtain the imaginary part of the dielectric constant at both
ω/2 and ω? (As in attached, the red solid and dashed lines)



Thanks!

Rongtian

[lyzhao]

Do you mean the imaginary part of the dielectric constant or SHG?
The dielectric constant is linear optical paramater and not SHG.

[pangrt]

Dear Zhao,
I think it is the imaginary part of the dielectric. How to obtain the dielectric constant at ω/2?

Thanks!

Rongtian

[lyzhao]

please see the first tutorial at http://www.attaccalite.com/lumen/tutorials.html.

[pangrt]

I notice that just an abs. of ω instead of ω/2?

Thanks!
Rongtian

[AmberLee123]

I think the abs. of ω/2 is just to extend the abs. of ω in the picture, ie. f(x/2) compared with f(x).
So there is no specially abs. of ω/2 in the output file from yambo. We just read abs. ω and then recalculate it.

Best.

[claudio]

Dear Rongtian

once you have the imaginary part of the dielectric constant, just plot it with the argument divided by two
for example in python:


plt.plot(EPS[:,0]/2., EPS[:,1],color="red", linewidth=3.0, linestyle="-", label="$\epsilon_2(\omega/2)$")
plt.plot(EPS[:,0], EPS[:,1],color="red", linewidth=3.0, linestyle="--",label="$\epsilon_2(\omega)$")

best
Claudio