EPW calculation crashes at the start.

[simran_kumari]

Hello,
I am doing some calculations using the EPW and got the following error in the CRASH file:
--------------------------------------------------------------------------------------------------------------------------
forrtl: severe (174): SIGSEGV, segmentation fault occurred
Image PC Routine Line Source
epw.x 00000000008433B1 Unknown Unknown Unknown
epw.x 00000000008414EB Unknown Unknown Unknown
epw.x 00000000006FBE44 Unknown Unknown Unknown
epw.x 00000000006FBC56 Unknown Unknown Unknown
epw.x 000000000066BBB9 Unknown Unknown Unknown
epw.x 0000000000673BE6 Unknown Unknown Unknown
libpthread-2.17.s 00002AB6EEE6E5E0 Unknown Unknown Unknown
epw.x 00000000009B7144 epw_setup_ 203 epw_setup.f90
epw.x 0000000000857757 MAIN__ 102 epw.f90
epw.x 0000000000407EDE Unknown Unknown Unknown
libc-2.17.so 00002AB6EF39EC05 __libc_start_main Unknown Unknown
epw.x 0000000000407DE9 Unknown Unknown Unknown
--------------------------------------------------------------------------------------------------------------------------

the epw.out file stops at the following point:

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Program EPW v.4.3.0 starts on 26Jul2018 at 11: 8:46

This program is part of the open-source Quantum ESPRESSO suite
for quantum simulation of materials; please cite
"P. Giannozzi et al., J. Phys.:Condens. Matter 21 395502 (2009);
"P. Giannozzi et al., J. Phys.:Condens. Matter 29 465901 (2017);
URL http://www.quantum-espresso.org",
in publications or presentations arising from this work. More details at
http://www.quantum-espresso.org/quote

Parallel version (MPI & OpenMP), running on 128 processor cores
Number of MPI processes: 128
Threads/MPI process: 1

MPI processes distributed on 8 nodes
K-points division: npool = 128

Reading data from directory:
./out/SC7.save/

IMPORTANT: XC functional enforced from input :
Exchange-correlation = PBE ( 1 4 3 4 0 0)
Any further DFT definition will be discarded
Please, verify this is what you really want


G-vector sticks info
--------------------
sticks: dense smooth PW G-vecs: dense smooth PW
Sum 925 451 199 194645 68547 18415

----2D----2D----2D----2D----2D----2D----2D----2D----2D----2D----2D----2D
The code is running with the 2D cutoff
Please refer to:
Sohier, T., Calandra, M., & Mauri, F. (2017),
Density functional perturbation theory for gated two-dimensional heterostructu
res:
Theoretical developments and application to flexural phonons in graphene.
Physical Review B, 96(7), 75448. https://doi.org/10.1103/PhysRevB.96.075448
----2D----2D----2D----2D----2D----2D----2D----2D----2D----2D----2D----2D

negative rho (up, down): 1.361E-01 0.000E+00


--------------------------------------------------------------------------------------------------------------------------

No matter what I cannot figure out what the problem is. Please help me out here. Thank you in advance.

regards,
Simran Kumari
THEOS, EPFL

[carla.verdi]

Hi,

At present the 2d cutoff is not implemented in EPW so this might be the cause of the crash.

Best,
Carla

[simran_kumari]

Thank you so much Carla to point that out. I tried again the calculations by removing the 2D cutoff(I did not redo the phonon calculations) in scf and nscf before performing the epw calculations. But still the EPW calculation did not run. It stopped at the same point with the same CRASH error.

Regards,
Simran

[sponce]

Dear Simran,

You need to remove the folder ./out/SC7.save/

Then indeed redo scf.in and nscf.in without 2D cutoff and it should work.

You should not have to redo the phonon I think.

Best wishes,
Samuel

[simran_kumari]

Hello,

Thank you so much for your reply. But it still doesn't work I will post my input file for you to see if something is wrong over dere. The code stops at line 203 in epw_setup.f90 and line102 in epw.f90. I have even tried with both ultrasoft and norm-conserving pseudopotentials but the error still remains. The input file is below:

------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
&inputepw
prefix = 'SC7',
amass(1) = XXXXX
amass(2) = XXXX
outdir = './out/'

ep_coupling = .true.
elph = .true.
kmaps = .false.
epbwrite = .true.
epbread = .false.

epwwrite = .true.
epwread = .false.

phonselfen = .true. !writes the phonon linewidths
elecselfen = .true !Calculate the electron self-energy from the el-ph interaction
a2f = .true.
etf_mem = 0
nbndsub = 6 !number of wannier functions to utilize
nbndskip = 10 !The number of bands lying below the disentanglement window in the calculation of the Wannier functions.
fermi_energy= -0.0610
wannierize = .true.
num_iter = 500
dis_froz_max= 2 !frozen states for Wan90
dis_froz_min= -3
dis_win_max = 4 ! disentanglement window
proj(1) = 'random'
wdata(1) = 'bands_plot = .true.'
wdata(2) = 'begin kpoint_path'
wdata(3) = 'G 0.00 0.00 0.00 K 0.00 0.50 0.00'
wdata(4) = 'K 0.00 0.50 0.00 M -0.33 0.66 0.00'
wdata(5) = 'M -0.33 0.66 0.00 G 0.00 0.00 0.00'
wdata(8) = 'end kpoint_path'
iverbosity = 2 !output only for the superconducting part


eps_acustic = 2.0 ! Lowest boundary for the phonon frequency
ephwrite = .true. ! Writes .ephmat files used when eliashberg = .true. , doesn't work with random k- or q-meshes and requires nkf1,nkf2,nkf3 to be multiple of nqf1,nqf2,nqf3.

fsthick = 0.4 ! eV Width of the Fermi surface window
eptemp = 300 ! K
degaussw = 0.10 ! eV
nsmear = 1
delta_smear = 0.04 ! eV

degaussq = 0.5 ! meV
nqstep = 500

eliashberg = .true.
laniso = .true. !the anisotropic Eliashberg equations are solved
limag = .true. !the imaginary-axis Eliashberg equations
lpade = .true. ! Pade approximants to continue the imaginary-axis Eliashberg equations to real-axis

conv_thr_iaxis = 1.0d-4

wscut = 1.0 ! eV Upper limit over frequency integration/summation in the Elisashberg eq

nstemp = 1
tempsmin = 15.00
tempsmax = 60.00

nsiter = 500

muc = 0.16

dvscf_dir = '/scratch/kumari/STRUCTURE_SET1/initial/XXXX/EPW/2D/save/'

nk1 = 14
nk2 = 14
nk3 = 1

nq1 = 7
nq2 = 7
nq3 = 1

! mp_mesh_k = .true.
nkf1 = 70
nkf2 = 70
nkf3 = 1

nqf1 = 70
nqf2 = 70
nqf3 = 1
/
8 cartesian
0.000000000000000E+00 0.000000000000000E+00 0.000000000000000E+00
0.000000000000000E+00 0.164957219772426E+00 0.000000000000000E+00
0.000000000000000E+00 0.329914439544851E+00 0.000000000000000E+00
0.000000000000000E+00 0.494871659317277E+00 0.000000000000000E+00
0.142857142857139E+00 0.247435829658638E+00 0.000000000000000E+00
0.142857142857139E+00 0.412393049431064E+00 0.000000000000000E+00
0.142857142857139E+00 0.577350269203489E+00 0.000000000000000E+00
0.285714285714279E+00 0.494871659317277E+00 0.000000000000000E+00

------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

Thanks a lot in advance.

Simran
THEOS, EPFL

[sponce]

Dear Simran,

1) Are the EPW tests working ? You can run them from q-e/test-suite and then do "make" there

2) Which version of QE are you using ? Is it a modified version ?

3) EPW only supports NC psp, not US.

Best wishes,
Samuel

[simran_kumari]

Dear Dr. Ponce,

To answer your questions:

1) I have tried an example with keeping everything exactly the same(version, no. of procs etc) and it works.

2) I am using QE-6.2.1 and EPW version 4.3.0.

3) I did not know that, but anyway I tried with the NC pseudo.

Thanks a lot in advance.

Regards,
Simran