Analyze the spectrum with ypp

[damao4361556]

Hi Daniele

1. I want to analyze the spectrum results with ypp, as shown in this tutorials, http://www.yambo-code.org/tutorials/SiH4/index.php setction [07]

Following the example, I need to choose the diagonalization solver. Then I type:

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yambo  -o b -k sex -y d

, this was suggested by the tutorials.

but there is no

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WRbsWF                       # [BSS] Write to disk excitonic the FWs

flag, in addition, the resulted yambo.in file is also different from the 06_BSE provided in the INPUTS directory.

But when I used the

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yambo  -o b -k sex -y d -V resp

, the WRbsWF flag was presented, but the yambo.in file is also different from the 06_BSE provided in the INPUTS directory.

The Response function is needed here? But it seems that it was not mentioned in the tutorials.

2. I have obtained BSE spectrum, the data is arranged like this:

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#  E/ev[1]    eps /Im[2] eps /Re[3] eps0/Im[4] eps0/Re[5] eps`/Im[6] eps`/Re[7]
#
   0.00000    0.00000   13.93249    0.00000   12.98278    0.00000   13.93249
 0.1010     0.1773E-1   13.94     0.1362E-1   12.99     0.1773E-1   13.94

Im and Re corresponds to the imaginary part and Real part of the dielectric constant, but what is the difference of col. 2-3 and col 4-5 and col 6-7.
In other words, which column of the data should we use to plot the spectrum?

thanks

[Daniele Varsano]

Dear Eric,

The Response function is needed here? But it seems that it was not mentioned in the tutorials.

You can calculate it before in a separated runlevel or in the same runlevel, so that yambo first calculate the screening and then build the BSE kernel.

, but what is the difference of col. 2-3 and col 4-5 and col 6-7.

2-3 is your BSE spectrum eps
4-5 is the independent-particle spectrum eps0
6-7 as you are using an iterative method to solve the BSE, col 6-7 gives you the spectrum at the n-1 iteration before converging, it is there to check the convergence of the spectrum.

Best,
Daniele