## Data output

Various technical topics such as parallelism and efficiency, netCDF problems, the Yambo code structure itself, are posted here.

### Re: Data output

Dear Andrea:
Thanks!
andrea marini wrote: Be carefull the iku stands for internal K units, and check the the alat used by Yambo is the same of the one used in the CPC paper. I already wrote somewhere else that alat in Yambo is a simple internal parameter used to rescale the k-pt vectors.

I then checked report file, and found i had misunderstood on iku.
For my calculation, (0.40, 0.0, 0.0) iku is (0.80, 0.0, 0.0) $2\pi/a$ . I attached the input setting for abinit and yambo rpt file. Please give me more comments on this issue .

However, without increasing damping energy (0.1 eV i adopted here following the CPC paper), I cannot find any other effective away to improve the smoothness of high tranfer monmenta curve. Can you give me some advices?
q9loss.png

Thanks
Best wishes,
Hai-Ping
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Hai-Ping LAN,
Department Of Electronics,
Peking University, 100871,Beijing, CHINA
hplan

Posts: 58
Joined: Thu Mar 26, 2009 2:26 pm

### Re: Data output

hplan wrote:However, without increasing damping energy (0.1 eV i adopted here following the CPC paper), I cannot find any other effective away to improve the smoothness of high tranfer monmenta curve. Can you give me some advices?

My advice is to look at the real/imaginary part of the dielectric function. A plasmon is a zero in both the real and imaginary part of epsilon and the oscillation you see must be reflected in some oscillations of the dielectric function. Once you find these oscillations you can trace them back in terms of band-to-band transitions trying to understand what is the source. Nevertheless in general the dielectric function is quite smooth near a plasmon frequency. So I do not see easy motivation that can explain your oscillations.

Try posting the plot of the real and imaginary part of the dielectric function using a large energy range and many many frequency points.

Cheers.
Andrea MARINI
Istituto di Struttura della Materia, CNR, (Italy)

andrea marini

Posts: 447
Joined: Mon Mar 16, 2009 4:27 pm

### Re: Data output

Dear Andrea:
Thanks !
andrea marini wrote:My advice is to look at the real/imaginary part of the dielectric function. A plasmon is a zero in both the real and imaginary part of epsilon and the oscillation you see must be reflected in some oscillations of the dielectric function. Once you find these oscillations you can trace them back in terms of band-to-band transitions trying to understand what is the source. Nevertheless in general the dielectric function is quite smooth near a plasmon frequency. So I do not see easy motivation that can explain your oscillations.

I examined the dielectric function, and found there were a lot oscillations. I tried to trace the bands transition, but it seems i cannot understand it .
eps.png

Try posting the plot of the real and imaginary part of the dielectric function using a large energy range and many many frequency points.

I increased the frequency points from 600 points to 1600 , and didnot find any explicit change in eels.
After including more bands, i then increased the frequency up to 80 eV. The situation also didnot change much, there were still many oscillations in eels.
eels.png

Regards,
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Hai-Ping LAN,
Department Of Electronics,
Peking University, 100871,Beijing, CHINA
hplan

Posts: 58
Joined: Thu Mar 26, 2009 2:26 pm

### Re: Data output

hplan wrote:equency points from 600 points to 1600 , and didnot find any explicit change in eels.
After including more bands, i then increased the frequency up to 80 eV. The situation also didnot change much, there were still many oscillations in eels.

The oscillations you see in the dielectric function may be related to the k-point mesh. Al is very complicate because the band width is large and the metallic character is diffucult to capture. To see if the reason for the oscillations is the too poor k-point sampling try reducing the broadening. You should see the oscillations increasing and clear delta-like peaks appearing in the imaginary part of the dielectric function.

If this is the case the only solution is too increase the size of the k-point mesh.
Andrea MARINI
Istituto di Struttura della Materia, CNR, (Italy)

andrea marini

Posts: 447
Joined: Mon Mar 16, 2009 4:27 pm

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