EPW Forum

Dear EPW users,

I'm new to EPW and willing to study electron-phonon coupling and superconductivity. I have performed all the required QE calculations and prepared an EPW input following the input documentation provided in EPW website. After submitting the job the code is running for several hours but no output is being generated. There must be something wrong in my input, and I'll be thankful if someone can solve my problem. Here is my EPW input:
*******************************
--
&inputepw
prefix = 'o_7.4t_p_1'
amass(1) = 15.9994
outdir = './'
iverbosity = 0
elph = .true.
ep_coupling = .true.
epbwrite = .true.
epwwrite = .true.
ephwrite = .true.
phonselfen = .true.
a2f = .true.
eliashberg = .true.
laniso = .true.
limag = .true.
lpade = .true.
dvscf_dir = '/save'
filelph = 'o_7.4t_p_1.elph'
muc = 0.1
nk1 = 8
nk2 = 8
nk3 = 8
nq1 = 4
nq2 = 4
nq3 = 4
nkf1 = 16
nkf2 = 16
nkf3 = 16
nqf1 = 16
nqf2 = 16
nqf3 = 16
nbndsub = 4
/
30 cartesian
0.000000000 0.000000000 0.000000000 1
-0.011813329 0.000000000 0.548262769 1
0.023626659 0.000000000 -1.096525539 1
0.000000000 0.408430849 0.000000000 1
-0.011813329 0.408430849 0.548262769 1
0.023626659 0.408430849 -1.096525539 1
0.000000000 -0.816861697 0.000000000 1
-0.011813329 -0.816861697 0.548262769 1
0.023626659 -0.816861697 -1.096525539 1
0.247731554 0.000000000 0.107972819 1
0.235918224 0.000000000 0.656235589 1
0.271358213 0.000000000 -0.988552720 1
0.259544883 0.000000000 -0.440289950 1
0.247731554 0.408430849 0.107972819 1
0.235918224 0.408430849 0.656235589 1
0.271358213 0.408430849 -0.988552720 1
0.259544883 0.408430849 -0.440289950 1
0.247731554 -0.816861697 0.107972819 1
0.235918224 -0.816861697 0.656235589 1
0.271358213 -0.816861697 -0.988552720 1
0.259544883 -0.816861697 -0.440289950 1
-0.495463107 0.000000000 -0.215945639 1
-0.507276437 0.000000000 0.332317131 1
-0.471836448 0.000000000 -1.312471177 1
-0.495463107 0.408430849 -0.215945639 1
-0.507276437 0.408430849 0.332317131 1
-0.471836448 0.408430849 -1.312471177 1
-0.495463107 -0.816861697 -0.215945639 1
-0.507276437 -0.816861697 0.332317131 1
-0.471836448 -0.816861697 -1.312471177 1

*******************************

Best regards
Subhodip

Dear Subhodip,

Which version of EPW and QE are you using?

I strongly recommend to use the latest QE 5.4 version that include EPW 4.0.

It seems you are missing some input like wannierize, proj etc for the Wannierization.

Best,

Samuel

Dear Samuel,

I have used EPW4.0 that is provided with QE5.4.0, but the calculations up to phonon were done in QE5.1.2. Is this the probable reason?

Inputs like wannierize, proj etc are missing, no doubt, but this should not be the reason for an empty .out file after several hours, I guess.

Best regards
Subhodip

Dear Subhodip,

I would advice to re-run the phonon with QE 5.4 to be sure yes.

Could you try running the first test ?

You can find it in EPW/tests/Inputs/t01.

Do you have an output with that?

Best,

Samuel

Dear Samuel,

I'll re-run the calculations with QE5.4.0.

I got normal output from the test run.

Best regards
Subhodip

Dear Samuel,

With QE5.4 only one line is being written in the .out file :

APPLICATION TERMINATED WITH THE EXIT STRING: Hangup (signal 1)

Best regards
Subhodip

Dear Samuel,

As I can realize this problem is related to parallelization, I was checking what happens if I vary -npool. here is what I got :

Fisrt of all I performed all the QE calculations with 48 cores (8 nodes, 6 processors per node).

As instructed in EPW documentation, I used -np 48 and -npool 48, and the output file showed only one line :
APPLICATION TERMINATED WITH THE EXIT STRING: Hangup (signal 1)

With -np 48 and -npool 8 the calculation started, but ended with the error :
stopped in DftiComputeBackward 5

With -np 48 and -npool 6 the calculation started with more progress than the previous case, and ended with the error :
Error in routine setphases_wrap (1) :
only one proc per pool

Best regards
Subhodip

Hello,

I can suggest the following tests:
1) Do the test/Inputs/t01 in parallel with 4 cores or 48 as you prefer
2) Start modifying the t01 input so that you end up with want you want.

That way you will be able to understand which input variable is problematic.
For example filelph = 'o_7.4t_p_1.elph' is a depreciated variable and will be remove in the next release.

Best,

Samuel

Ok....let's see how many trials lead to the successful run. Anyway, thanks for your suggestions Samuel.

Best regards
Subhodip