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by CHILLL
Mon Dec 27, 2021 6:14 pm
Forum: Running the code
Topic: Gap energy abruptly goes negative at high temperatures
Replies: 12
Views: 8396

Re: Gap energy abruptly goes negative at high temperatures

Hello Hari,

Yes, those values are very high indeed, but I am forced to increase wscut otherwise I get negative gap values again.
Is there maybe something else I can try?

Best,
Mikhail
by CHILLL
Thu Dec 23, 2021 11:31 am
Forum: Running the code
Topic: Gap energy abruptly goes negative at high temperatures
Replies: 12
Views: 8396

Re: Gap energy abruptly goes negative at high temperatures

Hello Hari, At the moment, for 16 K temperature I am trying Total number of frequency points nsiw( 1) = 550 Cutoff frequency wscut = 4.7690 with phonons not higher in energy than 200 meV. I am trying such high value because Total number of frequency points nsiw( 1) = 450 Cutoff frequency wscut = 3.9...
by CHILLL
Mon Dec 20, 2021 2:21 pm
Forum: Running the code
Topic: Gap energy abruptly goes negative at high temperatures
Replies: 12
Views: 8396

Re: Gap energy abruptly goes negative at high temperatures

Hello Hari, Your advice seems to be working, thanks a lot ! The only thing is that the higher the temperature I set in the calculation the more frequencies I need to make the gap positive. Is this normal behavior ? For all my previous materials, I used to just set a certain wscut (a very small one c...
by CHILLL
Wed Dec 15, 2021 6:59 am
Forum: Running the code
Topic: Gap energy abruptly goes negative at high temperatures
Replies: 12
Views: 8396

Re: Gap energy abruptly goes negative at high temperatures

Hello Hari, I did those tests already, and you are absolutely right: mustar 0 solves the problem. And when I start increasing it, the problem appears again at a value around 0.1(likely less than that). Unfortunately, results with mustar=0 are hardly suitable for a research, and there must be a reaso...
by CHILLL
Sat Dec 11, 2021 8:28 am
Forum: Running the code
Topic: Gap energy abruptly goes negative at high temperatures
Replies: 12
Views: 8396

Re: Gap energy abruptly goes negative at high temperatures

Hello Hari,

Here are the pictures you requested:
https://ibb.co/XV4C5CC

https://ibb.co/Qp0XTfg


Best,
Mikhail
by CHILLL
Fri Nov 19, 2021 1:57 pm
Forum: Running the code
Topic: Gap energy abruptly goes negative at high temperatures
Replies: 12
Views: 8396

Re: Gap energy goes negative at high temperatures

A little update to the question. In order to understand the problem better, I computed the EPC projected on the phonon band structure. and there is something I am concerned about. In the output file(see below) I see that lamda_tr and gamma_tr go negative. I think I have never seen it before. Could y...
by CHILLL
Thu Nov 11, 2021 10:08 pm
Forum: Running the code
Topic: Gap energy abruptly goes negative at high temperatures
Replies: 12
Views: 8396

Gap energy abruptly goes negative at high temperatures

Dear experts and users, I calculated superconducting properties of a material in EPW 5.4 and 5.1, and there is the same problem I see. The isotropic results Electron-phonon coupling strength = 0.8613774 Estimated Allen-Dynes Tc = 17.174912 K for muc = 0.13000 Estimated w_log in Allen-Dynes Tc = 33.0...
by CHILLL
Fri Nov 05, 2021 9:28 am
Forum: Running the code
Topic: Gap distribution yields a gap almost at zero energy.
Replies: 1
Views: 3453

Gap distribution yields a gap almost at zero energy.

Dear experts and users, I was calculating superconducting properties of a material, and I found that the gap distribution yields a gap almost at zero energy. The gap distribution : https://ibb.co/p4jDR3f It looks a bit odd. Do you think it can be correct ? I checked the wannierization/spreads, and t...
by CHILLL
Wed Oct 06, 2021 7:59 pm
Forum: Running the code
Topic: Anomalously large electron-phonon coupling
Replies: 1
Views: 2715

Anomalously large electron-phonon coupling

Dear experts and users, I have encountered a problem with anomalously large electron-phonon coupling in my calculations. I have read several posts concerning this problem, and done several checks to see if something was wrong. 1. Wannierization is alright. The spreads are small, and the W90 bands ar...
by CHILLL
Tue Oct 05, 2021 11:53 am
Forum: Running the code
Topic: Calculation gets frozen during/after wannierization stage
Replies: 3
Views: 3511

Re: Calculation gets frozen during/after wannierization stage

UPDATE: the was no problem. I made a mistake in the initial projections, so naturally the whole convergence of the disentanglement procedure was very bad. In 500 cycles it was still of the order to 10^(-1), but surprisingly it gave me very good bands (this actually confused me). But even with the ba...