Questions about TDDFT and RPA outputs

[nthiliniek]

Hi Yambo Team,

Since I wanted to analyze the optical spectrum, I switched to e-h space, But the two spectra I got from both RPA and TDALDA are almost similar. And, TDALDA calculation is more time-consuming compared to RPA with similar parameters. Is there something wrong with my input? Here I attach the reports and input files for both calculations.

outputs.zip

Thanks
Niranji

[Daniele Varsano]

Dear Niranji,

in bulk systems, alda approximations has very little effect wrt the RPA. It is more time-consuming as you have the alda extra term in the kernel.
What I find strange is that the spectra are practically identical to the IP spectrum, but I cannot spot anything wrong in the input file.
Have you already checked convergence with respect to the BSENGexx parameter?
Do you have the same effect when calculating the speturm in reciprocal space?

Best,
Daniele