Yambo Community Forum

Dear all,
After the BSE calculation of 2D material, I find the real part and imaginary of dielectric function shows "NaN".
How to fix this problem? Thanks, a lot.
# E/ev[1] EPS-Im[2] EPS-Re[3] EPSo-Im[4] EPSo-Re[5]
#
0.000000 NaN NaN 0.000000 1.044225
0.5025E-1 NaN NaN 0.1218E-4 1.044
0.1005 NaN NaN 0.2437E-4 1.044
0.1508 NaN NaN 0.3657E-4 1.044
0.2010 NaN NaN 0.4879E-4 1.044
0.2513 NaN NaN 0.6102E-4 1.044
0.3015 NaN NaN 0.7329E-4 1.044
0.3518 NaN NaN 0.8559E-4 1.044
0.4020 NaN NaN 0.9793E-4 1.044
0.4523 NaN NaN 0.1103E-3 1.044
0.5025 NaN NaN 0.1227E-3 1.044
0.5528 NaN NaN 0.1352E-3 1.044
0.6030 NaN NaN 0.1478E-3 1.044
0.6533 NaN NaN 0.1604E-3 1.044
0.7035 NaN NaN 0.1731E-3 1.045
0.7538 NaN NaN 0.1859E-3 1.045
0.8040 NaN NaN 0.1987E-3 1.045
0.8543 NaN NaN 0.2117E-3 1.045
0.9045 NaN NaN 0.2248E-3 1.045
0.9548 NaN NaN 0.2379E-3 1.045
1.005 NaN NaN 0.2512E-3 1.045
1.055 NaN NaN 0.2646E-3 1.045
1.106 NaN NaN 0.2781E-3 1.045
1.156 NaN NaN 0.2918E-3 1.045

Dear Yimin,
Can you please post your input and report file?
In order to attach you need to zip or rename the files with an allowed suffix e.g. .txt

Best,
Daniele

Thanks for your reply.
I have fixed the problem.

Dear Developers,

I used the BSE-slepc solver for metallic systems. After DFT+BSE calculation (without ndb.QP correction file), the dielectric functions gave "NaN". I removed the ndb.kindx and ndb.gops files in the "SAVE" folder and then I ran yambo command but "NaN" didn't fix. I attached input and report files.

Best regards,
Zafer

Dear Zafer,
my suggestion is to first try the Haydock solver and see if the spectrum has negative energy poles.
You would see them as negative intensity peaks in the positive frequency axise, or positive intensity peaks in the negative frequency axis.
In case you would probably need some QP corrections.

Also please notice that we very recently released a fix for the SLEPC
You would need to download the last version of 5.0 or the pre-release 5.1 for that.
From here: https://github.com/yambo-code/yambo/tree/5.0 (or here https://github.com/yambo-code/yambo/tree/5.1)
push on the green "Code" button and then do "download zip" (git clone works also fine as an alternative.

Best,
D.

Dear Davide,

Thank you for your reply. I solved the "NaN" problem by changing the BS_CPU values and trying on another server. I attached the new report and log files. Could the problem be due to memory?
Yambo version 5.0.4 is very nice.

Best regards,
Zafer

Ok. Glad that it worked in the end.
No idea of which could have been the issue.

Best,
D.