Problem in pp.py script in Pb example folder

Running the code
1

Dear moderator,

I would like to point out one probable error I encountered while using "python pp.py" before performing scf and nscf calculations in the following example folder for Lead (pb): espresso-5.4.0/EPW/examples/pb/woSOC/phonons

After running ../../../../bin/ph.x < ph.in >& ph.out &, I obtain following files: pb.dyn1, pb.dyn2, pb.dyn3 … pb.dyn16.

To copy these files into the save folder before proceeding to epw calculations, I use the script pp.py (located in the same folder as the above *.dyn files). But it resulted in error something like "cp: cannot stat `pb.dyn1.xml’: No such file or directory". This error is self-explanatory as the files to be copied into the save folder are named as pb.dyn.iqpt (like pb.dyn1, pb.dyn2 and so on) without ".xml" extension.

Currently the following command is being used in pp.py script.

[code:3eva1xxq]os.system(‘cp ‘+prefix+’.dyn’+str(iqpt)+‘.xml save/’+prefix+‘.dyn_q’+label+‘.xml’)[/code:3eva1xxq]

I think the ".xml" part should be removed from the script.

Please correct me if I am wrong here.

Secondly, I noticed that in Fig. 4 on the documentation page ([url:3eva1xxq]http://epw.org.uk/Documentation/FCCLead[/url:3eva1xxq]), transport coupling strength \lambda_{tr} is thin dashed blue line (according to the figure caption) but in the figure it is located above the red line. Although it does not matter much, but looks a big ambiguous in the figure.

Thanks and best wishes

Ankit

2

Dear Ankit,

Thank you for your interest in EPW.

You are correct. Calculation with SOC generate dyn file with the .xml extension.
Therefore there might be an issue in the example indeed.

At the moment only the /tests/ are tested in the testfarm (the examples are not).
Thank you for reporting it.

The figure 4 is not only ambiguous, its actually wrong. I need to update it. There was a bug with the calculation of the electronic velocities. The dashed line are therefore wrong (the plain lines are ok).

This bug correction will be release in Sep along the with new version of QE 6.0

I will update the picture asap.

Best,

Samuel

3

Hello,

I’ve updated the figure 4 for the tutorial

http://epw.org.uk/uploads/Documentation/Pb_a2Fvstr2.png

Best,

Samuel

4

Dear Dr. Ponc,

Thank you very much for a quick response.

I have just started with the EPW tutorials before I calculate the electron-phonon coupling parameter (lambda) for fcc-L12 phase of Al3Sc precipitate for one of my papers.

In case I face any issues, I will post my query here. I already have the required number calculated from abinit.8.0.7 version. It would be nice to compare the result with EPW as well.

Many thanks!

Bests

Ankit

5

Dear Ankit,

That would be very interesting indeed !

Out of curiosity, what have you used in the case of Abinit? Anaddb or the temperature python script ?

Best,
Samuel

6

Dear Dr. Ponc,

I used [i:15dyycfk]anaddb[/i:15dyycfk] module of Abinit using the LDA functional. AFAIK, GGA is not yet implemented in Abinit for the calculation of electron-phonon coupling parameters.

Bests

Ankit